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Support? Bug reports? Please read G3 for what information is required to get your problem solved as quickly as possible.
Note that this FAQ is occasionally updated from the Git repository and speaks in the past tense ("since") about a fetchmail release that is not yet available. Please try a release candidate for that version in case you need the new option.
If you have a question or answer you think ought to be added to this FAQ list, file it to one of the trackers at our BerliOS project site or post to one of the fetchmail mailing lists (see below).
Fetchmail is a one-stop solution to the remote mail retrieval problem for Unix machines, quite useful to anyone with an intermittent or dynamic-IP connection to a remote mailserver, SLIP or PPP dialup, or leased line when SMTP isn't desired. Fetchmail can collect mail using any variant of POP or IMAP and forwards to a the local SMTP (via TCP socket) or LMTP (via TCP or Unix socket) listener or into an MDA program, enabling all the normal forwarding/filtering/aliasing mechanisms that would apply to local mail or mail arriving via a full-time TCP/IP connection.
Fetchmail is not a toy or a coder's learning exercise, but an industrial-strength tool capable of transparently handling every retrieval demand from those of a simple single-user ISP connection up to mail retrieval and rerouting for an entire client domain. Fetchmail is easy to configure, unobtrusive in operation, powerful, feature-rich, and well documented.
Fetchmail is Open Source Software. The openness of the sources enables you to review and customize the code, and contribute your changes.
A former fetchmail maintainer once claimed that Open Source software were the strongest quality assurance, but the current maintainers do not believe that open source alone is a criterion for quality – the remotely exploitable POP3 vulnerability (CVE-2005-2335) lingered undiscovered in fetchmail's code for years, which is a hint that open source code does not audit itself.
Fetchmail is licensed under the GNU General Public License v2. Details, including an exception that allows linking against OpenSSL, are in the COPYING file in the fetchmail distribution.
If you found this FAQ in the distribution, see the README for fetchmail's full feature list.
The latest HTML FAQ is available alongside the latest fetchmail sources at the fetchmail home page: http://www.fetchmail.info/. You can also usually find both in the POP mail tools directory on iBiblio.
A text dump of this FAQ is included in the fetchmail distribution. Because it freezes at distribution release time, it may not be completely current.
The first thing you should to is to upgrade to the newest version of fetchmail, and then see if the problem reproduces. So you'll probably save us both time if you upgrade and test with the latest version before sending in a bug report.
Bugs will be fixed, provided you include enough diagnostic information for me to go on. Send bugs to fetchmail-users. When sending bugs or asking for help, please do not make up information except your password and please report the following:
It is very important that the transcript include your POP/IMAP server's greeting line, so I can identify it in case of server problems. This transcript will not reveal your passwords, which are specially masked out precisely so transcripts can be passed around.
If you have FTP access to your remote mail account, and you have any suspicion that the bug was triggered by a particular message, please include a copy of the message that triggered the bug.
If your bug is something that used to work but stopped working when you upgraded, then you can help pin the bug down by trying intermediate versions of fetchmail until you identify the revision that broke your feature. The smart way to do this is by binary search on the version sequence. First, try the version halfway between your last good one and the current one. If it works, the failure was introduced in the upper half of the sequence; if it doesn't, the failure was introduced in the lower half. Now bisect that half in the same way. In a very few tries, you should be able to identify the exact adjacent pair of versions between which your bug was introduced. Please include session transcripts (as described in the last bullet point above) of both the working and failing versions. Often, the source of the problem can instantly identified by looking at the differences in protocol transactions.
It may helpful if you include your .fetchmailrc file, but not necessary unless your symptom seems to involve an error in configuration parsing. If you do send in your .fetchmailrc, mask the passwords first! Otherwise, fetchmail -V – as directed above – will usually suffice.
If fetchmail seems to run and fetch mail, but the headers look mangled (that is, headers are missing or blank lines are inserted in the headers) then read the FAQ items in section X before submitting a bug report. Pay special attention to the item on diagnosing mail mangling. There are lots of ways for other programs in the mail chain to screw up that look like fetchmail's fault, but you may be able to fix these by tweaking your configuration.
If the bug involves a core dump or hang, a gdb stack trace is good to have. (Bear in mind that you can attach gdb to a running but hung process by giving the process ID as a second argument.) You will need to reconfigure with:
CFLAGS=-g LDFLAGS=" " ./configure
Then rebuild in order to generate a version that can be traced with a debugger such as gdb, dbx or idb.
Best of all is a mail file which, when fetched, will reproduce the bug under the latest (current) version.
Any bug I can reproduce will usually get fixed quite quickly. Bugs I can't reproduce are a crapshoot. If the solution isn't obvious when I first look, it may evade me for a long time (or to put it another way, fetchmail is well enough tested that the easy bugs have long since been found). So if you want your bug fixed rapidly, it is not just sufficient but necessary that you give me a way to easily reproduce it.
If it's reasonable for fetchmail and cannot be solved with reasonable effort outside of fetchmail, perhaps.
You can do spam filtering better with procmail or maildrop on
the server side and (if you're the server sysadmin) sendmail.cf
domain exclusions. If you really want fetchmail to do it from the
client side, use a preconnect command to call
mailfilter.
You can do other policy things better with the
mda option and script wrappers around fetchmail. If
it's a prime-time-vs.-non-prime-time issue, ask yourself whether a
wrapper script called from crontab would do the job.
fetchmail's first job is transport though, and it should do this well. If a feature would cause fetchmail to deteriorate in other respects, the feature will probably not be added.
For reasons fetchmail doesn't have other commonly-requested features (such as password encryption, or multiple concurrent polls from the same instance of fetchmail) see ESR's design notes. Note that this document is partially obsoleted by the updated design notes.
The second-most-requested feature for fetchmail, after
content-based filtering, is the ability to have it remove messages
from a maildrop after N days, typically to be used with the
keep option. Several messaging programs with graphical
user interface support this feature.
This feature is not yet implemented. It may be at a future date, spare time of developers permitting.
For the time being, the contrib/ directory contains some unsupported tools that may help, namely mold-remover.py and delete-later.
There is a fetchmail-users list <fetchmail-users@lists.berlios.de> for bug reports and people who want to discuss configuration issues of fetchmail. Please see G3 above for information you need to report. It's a Mailman list, see http://lists.berlios.de/mailman/listinfo/fetchmail-users for info and subscription.
There is a fetchmail-devel list <fetchmail-devel@lists.berlios.de> for people who want to discuss fixes and improvements in fetchmail and help co-develop it. It's a Mailman list, which you can sign up for at http://lists.berlios.de/mailman/listinfo/fetchmail-devel.
There is also an announcements-only list, <fetchmail-announce@lists.berlios.de>, which you can sign up for at http://lists.berlios.de/mailman/listinfo/fetchmail-announce.
Eric S. Raymond also considered fetchmail development a sociological experiment, an extended test to see if my theory about the critical features of the Linux development model is correct.
He considers the experiment a success. He wrote a paper about it titled The Cathedral and the Bazaar which was first presented at Linux Kongress '97 in Bavaria and very well received there. It was also given at Atlanta Linux Expo, Linux Pro '97 in Warsaw, and the first Perl Conference, at UniForum '98, and was the basis of an invited presentation at Usenix '98. The folks at Netscape told ESR it helped them decide to give away the source for Netscape Communicator.
If you're reading a non-HTML dump of this FAQ, you can find the paper on the Web with a search for that title.
Fetchmail will work with any POP, IMAP, ETRN, or ODMR server that conforms to the relevant standards/RFCs (and even some outright broken ones like Microsoft Exchange and Novell GroupWise). This doesn't mean it works equally well with all, however. POP2 servers, and POP3 servers without UIDL, limit fetchmail's capabilities in various ways described on the manual page.
Most modern Unixes (and effectively all Linux/*BSD systems) come with POP3 support preconfigured (but beware of the horribly broken POP3 server mentioned in D2). An increasing minority also feature IMAP (you can detect IMAP support by using the 'Probe for supported protocols' function in the fetchmailconf utility - unfortunately it does not detect SSL-wrapped variants).
If you have the option, we recommend using or installing an IMAP4rev1 or UIDL-capable POP3 server.
A decent POP3/IMAP server that has recently become popular is Dovecot.
Avoid qmail, it's broken and unmaintained.
Fetchmail will work with all popular mail transport programs. It also doesn't care which user agent you use, and user agents are as a rule almost equally indifferent to how mail is delivered into your system mailbox. So any of the popular Unix mail agents – elm, pine, mh, or mutt – will work fine with fetchmail.
All this having been said, I can't resist putting in a discreet plug for mutt. Mutt's interface is only a little different from that of its now-moribund ancestor elm, but its flexibility and excellent handling of MIME and PGP put it in a class by itself. You won't need its built-in POP3 support, though.
Depending on what your mail server you are talking to, this ranges from trivial to impossible. It may even be next to useless.
In general there is little point in trying to secure your fetchmail transaction unless you trust the security of the server host you are retrieving mail from. Your vulnerability is more likely to be an insecure local network on the server end (e.g. to somebody with a TCP/IP packet sniffer intercepting Ethernet traffic between the modem concentrator or DSL POP you dial in to and the mailserver host).
Having realized this, you need to ask whether password encryption alone will really address your security exposure. If you think you might be snooped between server and client, it's better to use end-to-end encryption such as GnuPG (see below) on your whole mail stream so none of it can be read. One of the advantages of fetchmail over conventional SMTP-push delivery is that you may be able to arrange encryption by using ssh(1); see K3.
Note that ssh is not a complete privacy solution either, as your mail could have been snooped in transit to your POP server from wherever it originated. For best security, agree with your correspondents to use a tool such as GnuPG (Gnu Privacy Guard) or PGP (Pretty Good Privacy).
If ssh/sshd isn't available, or you find it too complicated for you to set up, password encryption will at least keep a malicious cracker from deleting your mail, and require him to either tap your connection continuously or crack root on the server in order to read it.
You can deduce what encryptions your mail server has available
by looking at the server greeting line (and, for IMAP, the response
to a CAPABILITY query). Do a fetchmail -v to see
these, or telnet direct to the server port (110 for POP3, 143 for
IMAP).
If your mailserver is using IMAP 2000, it'll have CRAM-MD5 support built in. Fetchmail autodetects this; you can skip the rest of this section.
The POP3 facility you are most likely to have available is APOP.
This is a POP3 feature supported by many servers (fetchmailconf's
autoprobe facility will detect it and tell you if you have it). If
you see something in the greeting line that looks like an
angle-bracket-enclosed Internet address with a numeric left-hand
part, that's an APOP challenge (it will vary each time you log in).
For some hosts, you need to register a secret on the host (using
popauth(8) or some program like that). Specify the
secret as your password in your .fetchmailrc; it will be used to
encrypt the current challenge, and the encrypted form will be sent
back the the server for verification. Note that APOP is no longer
considered secure since March 2007.
Alternatively, you may have Kerberos available. This may require you to set up some magic files in your home directory on your client machine, but means you can omit specifying any password at all.
Fetchmail supports two different Kerberos schemes. One is a POP3 variant called KPOP; consult the documentation of your mail server to see if you have it (one clue is the string "krb-IV" in the greeting line on port 110). The other is an IMAP and POP3 facility described by RFC1731 and RFC1734. You can tell if this one is present by looking for AUTH=KERBEROS_V4 in the CAPABILITY response.
If you are fetching mail from a CompuServe POP3 account, you can use their RPA authentication. See I1 for details. If you are fetching mail from Microsoft Exchange using IMAP, you will be able to use NTLM.
Your POP3 server may have the RFC1938 OTP capability to use one-time passwords (if it doesn't, you can get OTP patches for the 2.2 version of the Qualcomm popper from Craig Metz). To check this, look for the string "otp-" in the greeting line. If you see it, and your fetchmail was built with OPIE support compiled in (see the distribution INSTALL file), fetchmail will detect it also. When using OTP, you will specify a password but it will not be sent en clair.
You can get both POP3 and IMAP OTP patches from Craig Metz at http://www.inner.net/opie.
These patches use a SASL authentication method named "X-OTP" because there is not currently a standard way to do this; fetchmail also uses this method, so the two will interoperate happily. They better, because this is how Craig gets his mail ;-)
Finally, you can use SSL for complete end-to-end encryption if you have an SSL-enabled mailserver.
Yes. In order to avoid giving indigestion to certain picky MTAs (notably exim), fetchmail always makes the RCPT TO address it feeds the MTA a fully qualified one with a hostname part. Normally it does this by appending @ and "localhost", but when you are using Kerberos or ETRN mode it will append @ and your machine's fully-qualified domain name (FQDN).
Appending the FQDN can create problems when fetchmail is running in daemon mode and outlasts the dynamic IP address assignment your client machine had when it started up.
Since the new IP address (looked up at RCPT TO interpretation time) doesn't match the original, the most benign possible result is that your MTA thinks it's seeing a relaying attempt and refuses. More frequently, fetchmail will try to connect to a nonexistent host address and time out. Worst case, you could up forwarding your mail to the wrong machine!
Use the smtpaddress option to force the appended
hostname to one with a (fixed) IP address of 127.0.0.1 in your
/etc/hosts. (The name 'localhost' will usually work;
or you can use the IP address itself.)
Only one fetchmail option interacts directly with your IP
address, 'interface'. This option can be used to set
the gateway device and restrict the IP address range fetchmail will
use. Such a restriction is sometimes useful for security reasons,
especially on multihomed sites. See C3.
I recommend against trying to set up the interface
option when initially developing your poll configuration – it's
never necessary to do this just to get a link working. Get the link
working first, observe the actual address range you see on
connections, and add an interface option (if you need
one) later.
You can't use ETRN if you have a dynamic IP address (your ISP changes your IP address occasionally, possibly with every connect). You need to have your own registered domain and a definite IP address registered for that domain. The server needs to be configured to accept mail for your domain but then queue it to forward to your machine. ETRN just tells to server to flush its queue for your domain. Fetchmail doesn't actually get the mail in that case.
You can use On-Demand Mail Relay (ODMR) with a dynamic IP address; that's what it was designed for, and it provides capabilities very similar to ETRN. Unfortunately ODMR servers are still not yet widely deployed, as of 2006.
If you're using a dynamic-IP configuration, one other (non-fetchmail) problem you may run into with outgoing mail is that some sites will bounce your email because the hostname you're giving them isn't real (and doesn't match what they get doing a reverse DNS on your dynamically-assigned IP address). If this happens, you need to hack your sendmail so it masquerades as your host. Setting
DMsmarthost.here
in your sendmail.cf will work, or you can set
MASQUERADE_AS(smarthost.here)
in the m4 configuration and do a reconfigure. (In both cases,
replace smarthost.here with the actual name of your
mailhost.) See the sendmail FAQ for
more details.
No. You can use fetchmail with SOCKS, the standard tool for indirecting TCP/IP through a firewall. You can find out about SOCKS, and download the SOCKS software including server and client code, at the SOCKS distribution site.
The specific recipe for using fetchmail with a firewall is at K1
A user asks: but how do we send mail out to the POP3 server? Do I need to implement another tool or will fetchmail do this too?
Fetchmail only handles the receiving side. The sendmail or other preinstalled MTA on your client machine will handle sending mail automatically; it will ship mail that is submitted while the connection is active, and put mail that is submitted while the connection is inactive into the outgoing queue.
Normally, sendmail is also run periodically (every 15 minutes on most Linux systems) in a mode that tries to ship all the mail in the outgoing queue. If you have set up something like pppd to automatically dial out when your kernel is called to open a TCP/IP connection, this will ensure that the mail gets out.
Fetchmail is fully Y2K-compliant.
Fetchmail could theoretically have problems when the 32-bit time_t counters roll over in 2038, but I doubt it. Timestamps aren't used for anything but log entry generation. Anyway, if you aren't running on a 64-bit machine by then, you'll deserve to lose.
No. Fetchmail is a mail transport agent, best understood as a protocol gateway between POP3/IMAP servers and SMTP. Disconnected operation requires an elaborate interactive client. It's a very different problem.
Fetchmail streams message bodies line-by-line; the most core it ever requires per message is enough memory to hold the RFC822 header, and that storage is freed when body processing begins. It is, accordingly, quite economical in its use of memory. It will store the UID or UIDL data in core however, which can become considerable if you are keeping lots of messages on the server.
After startup time, a fetchmail running in daemon mode stats its configuration file once per poll cycle to see whether it has changed and should be rescanned. Other than that, a fetchmail in normal operation doesn't touch the disk at all; that job is left up to the MTA or MDA the fetchmail talks to.
Fetchmail's performance is usually bottlenecked by latency on the POP server or (less often) on the TCP/IP link to the server. This is not a problem readily solved by tuning fetchmail, or even by buying more TCP/IP capacity (which tends to improve bandwidth but not necessarily latency).
As of release 6.3.0, fetchmail's
Makefile[.in] should work flawlessly with BSD's portable make used on
FreeBSD. With older releases, use GNU make (usually installed as
gmake; otherwise try pkg_add -r gmake).
fetchmail 6.3.0 and newer ship with the lexer and parser in .c formats, so you do not need to use lex unless you hacked the .l or .y files.
fetchmail's lexer has been developed with GNU flex and uses some of its specialties, so the lexer cannot be compiled with the lex tools shipped by some UNIX vendors (HP, SGI, Sun).
If you get errors resembling these:
mxget.o(.text+0x35): undefined referenceto '__res_search' mxget.o(.text+0x99): undefined reference to '__dn_skipname' mxget.o(.text+0x11c): undefined reference to '__dn_expand' mxget.o(.text+0x187): undefined reference to '__dn_expand' make: *** [fetchmail] Error 1
then you must add "-lresolv" to the LOADLIBS line in your Makefile once you have installed the 'bind' package.
If you get link errors involving dcgettext, like these:
rcfile_y.o: In function 'yyparse': rcfile_y.o(.text+0x3aa): undefined reference to 'dcgettext__' rcfile_y.o(.text+0x4f2): undefined reference to 'dcgettext__' rcfile_y.o(.text+0x5ee): undefined reference to 'dcgettext__' rcfile_y.o: In function 'yyerror': rcfile_y.o(.text+0xc7c): undefined reference to 'dcgettext__' rcfile_y.o(.text+0xcc8): undefined reference to 'dcgettext__' rcfile_y.o(.text+0xdf9): more undefined references to 'dcgettext__' follow
install an up to date version of GNU gettext, reconfigure and rebuild fetchmail. If that does not help, reconfigure with '--disable-nls' added to the "./configure" command and rebuild.
Reconfigure with --disable-nls and recompile.
The netsec option was discontinued and needs to be removed.
If you were using ETRN mode, change your smtphost option to a fetchdomains option.
The 'via localhost' special case for use with ssh tunnelling is gone. Use the %h feature of plugin instead.
In 5.6.8, the preauth keyword and option were changed back to auth. The preauth synonym will still be supported through a few more point releases.
The imap-gss, imap-k4, and imap-login protocol types are gone. This is a result of a major re-factoring of the authentication machinery; fetchmail can now use Kerberos V4 and GSSAPI not just with IMAP but with POP3 servers that have RFC1734 support for the AUTH command.
When trying to identify you to an IMAP or POP mailserver, fetchmail now first tries methods that don't require a password (GSSAPI, KERBEROS_IV); then it looks for methods that mask your password (CRAM-MD5, X-OTP); and only if it the server doesn't support any of those will it ship your password en clair.
Setting the preauth option to any value other than 'password' will prevent from looking for a password in your .netrc file or querying for it at startup time.
In 5.1.0, the auth keyword and option were changed to preauth.
If the dns option is on (the default), you may need
to make sure that any hostname you specify (for mail hosts or for
an SMTP target) is a canonical fully-qualified hostname). In order
to avoid DNS overhead and complications, fetchmail no longer tries
to derive the fetchmail client machine's canonical DNS name at
startup.
Just after the 'via' option was introduced, I
realized that the interactions between the 'via',
'aka', and 'localdomains' options were
out of control. Their behavior had become complex and confusing, so
much so that I was no longer sure I understood it myself. Users
were being unpleasantly surprised.
Rather than add more options or crock the code, I re-thought it. The redesign simplified the code and made the options more orthogonal, but may have broken some complex multidrop configurations.
Any multidrop configurations that depended on the name just
after the 'poll' or 'skip' keyword being
still interpreted as a DNS name for address-matching purposes, even
in the presence of a 'via' option, will break.
It is theoretically possible that other unusual configurations (such as those using a non-FQDN poll name to generate Kerberos IV tickets) might also break; the old behavior was sufficiently murky that we can't be sure. If you think this has happened to you, contact the maintainer.
The 'remote' keyword has been changed to
'folder'. If you try to use the old keyword, the
parser will utter a warning.
It could be because you're using a .fetchmailrc that's written
in the old popclient syntax without an explicit
'username' keyword leading the first user entry
attached to a server entry.
This error can be triggered by having a user option such as
'keep' or 'fetchall' before the first
explicit username. For example, if you write
poll openmail protocol pop3
keep user "Hal DeVore" there is hdevore here
the 'keep' option will generate an entire user
entry with the default username (the name of fetchmail's invoking
user).
The popclient compatibility syntax was removed in 4.0. It complicated the configuration file grammar and confused users.
The 'interface', 'monitor' and
'batchlimit' options changed after 2.8.
They used to be global options with 'set' syntax
like the batchlimit and logfile options. Now they're per-server
options, like 'protocol'.
If you had something like
set interface = "sl0/10.0.2.15"
in your .fetchmailrc file, simply delete that line and insert 'interface sl0/10.0.2.15' in the server options part of your 'defaults' declaration.
Do similarly for any 'monitor' or
'batchlimit' options.
Either upgrade to a post-5.0.5 fetchmail or put string quotes around it. :-)
The configuration file parser in older fetchmail versions treated any all-numeric token as a number, which confused it when it was expecting a name. String quoting forces the token's class.
The lexical analyzer in 5.0.6 and beyond is smarter and assumes any token following "username" or "password" is a string.
See F2. You're caught in an unfortunate crack between the newer-style syntax for negated options ('no keep', 'no rewrite' etc.) and the older style run-on syntax ('nokeep', 'norewrite' etc.).
Upgrade to a 5.0.6 or later fetchmail, or put string quotes around your token.
The most common cause of mysterious parse errors is putting a server option after a user option. Check the manual page; you'll probably find that by moving one or more options closer to the 'poll' keyword you can eliminate the problem.
Yes, I know these ordering restrictions are hard to understand. Unfortunately, they're necessary in order to allow the 'defaults' feature to work.
Ian T. Zimmerman <itz@rahul.net> asked:
On the machine where I'm the only real user, I run fetchmail as root from a cron job, like this:
fetchmail -u "itz" -p POP3 -s bolero.rahul.net
This used to work as is (with no .fetchmailrc file in root's home directory) with the last version I had (1.7 or 1.8, I don't remember). But with 2.0, it RECPs all mail to the local root user, unless I create a .fetchmailrc in root's home directory containing:
skip bolero.rahul.net proto POP3
user itz is itz
It won't work if the second line is just "user
itz". This is silly.
It seems fetchmail decides to RECP the 'default local user' (i.e. the uid running fetchmail) unless there are local aliases, and the 'default' aliases (itz->itz) don't count. They should.
Answer:
No they shouldn't. I thought about this for a while, and I don't much like the conclusion I reached, but it's unavoidable. The problem is that fetchmail has no way to know, in general, that a local user 'itz' actually exists.
"Ah!" you say, "Why doesn't it check the password file to see if the remote name matches a local one?" Well, there are two reasons.
One: it's not always possible. Suppose you have an SMTP host declared that's not the machine fetchmail is running on? You lose.
Two: How do you know server itz and SMTP-host itz are the same person? They might not be, and fetchmail shouldn't assume they are unless local-itz can explicitly produce credentials to prove it (that is, the server-itz password in local-itz's .fetchmailrc file.).
Once you start running down possible failure modes and thinking about ways to tinker with the mapping rules, you'll quickly find that all the alternatives to the present default are worse or unacceptably more complicated or both.
The easiest way to dispatch fetchmail on logout (which will work reliably only if you have just one login going at any time) is to arrange for the command 'fetchmail -q' to be called on logout. Under bash, you can arrange this by putting 'fetchmail -q' in the file '~/.bash_logout'. Most csh variants execute '~/.logout' on logout. For other shells, consult your shell manual page.
Automatic startup/shutdown of fetchmail is a little harder to arrange if you may have multiple login sessions going. In the contrib subdirectory of the fetchmail distribution there is some shell code you can add to your .bash_login and .bash_logout profiles that will accomplish this. Thank James Laferriere <babydr@nwrain.net> for it.
Some people start up and shut down fetchmail using the ppp-up and ppp-down scripts of pppd.
This depends a lot on your local networking configuration (and right now you can't use it at all except under Linux and the newer BSDs). However, here are some important rules of thumb that can help. If they don't work, ask your local sysop or your Internet provider.
First, you may not need to use --interface at all. If your machine only ever does SLIP or PPP to one provider, it's almost certainly by a point to point modem connection to your provider's local subnet that's pretty secure against snooping (unless someone can tap your phone or the provider's local subnet!). Under these circumstances, specifying an interface address is fairly pointless.
What the option is really for is sites that use more than one provider. Under these circumstances, typically one of your provider IP addresses is your mailserver (reachable fairly securely via the modem and provider's subnet) but the others might ship your packets (including your password) over unknown portions of the general Internet that could be vulnerable to snooping. What you'll use --interface for is to make sure your password only goes over the one secure link.
To determine the device:
To determine the address and netmask:
To illustrate the rule for dynamic IP addresses, let's suppose you're hooked up via SLIP and your IP provider tells you that the dynamic address pool is 255 addresses ranging from 205.164.136.1 to 205.164.136.255. Then
interface "sl0/205.164.136.0/255.255.255.0"
would work. To range over any value of the last two octets (65536 addresses) you would use
interface "sl0/205.164.0.0/255.255.0.0"
This answer covers versions of sendmail from 8.9.3-20 (the version installed in Red Hat 6.2) upwards. If you have an older version, upgrade to sendmail 8.9.
Stock sendmails can now do anti-spam exclusions based on a database of filter rules. The human-readable form of the database is at /etc/mail/access. The database itself is at /etc/mail/access.db.
The table itself uses email addresses, domain names, and network numbers as keys. For example,
spammer@aol.com REJECT cyberspammer.com REJECT 192.168.212 REJECT
would refuse mail from spammer@aol.com, any user from cyberspammer.com (or any host within the cyberspammer.com domain), and any host on the 192.168.212.* network. (This feature can be used to do other things as well; see the sendmail documentation for details)
To actually set up the database, run
makemap hash deny <deny
in /etc/mail.
To test, send a message to your mailing address from that host and then pop off the message with fetchmail, using the -v argument. You can monitor the SMTP transaction, and when the FROM address is parsed, if sendmail sees that it is an address in spamlist, fetchmail will flush and delete it.
Under no circumstances put your mailhost or any host you accept mail from using fetchmail into your reject file. You will lose mail if you do this!!!
Use the interval keyword on the ones that should be checked less often. For example, if you do a poll every 5 minutes, and want to poll some mailboxes every 5 minutes and some every 30 minutes, use something like this:
poll mainsite.example.com proto pop3 user .... poll secondary.example.com proto pop3 interval 6 user ...
Then secondary.example.com will be polled every 6th time that mainsite.example.com is polled, which with a polling interval of every 5 minutes means that secondary.example.com will be polled every 30 minutes.
Often, startup scripts have a different environment than an interactive login shell. For instance, $HOME might point to "/root" when you are logged in as root, but it might be either unset, or set to "/" when the startup scripts are running. That means fetchmail at startup can't find the .fetchmailrc.
Pick a location (such as /etc/fetchmailrc) and use fetchmail's -f option to point fetchmail at it. That should solve the problem.
To forward mail to a host other than the one you are running
fetchmail on, use the smtphost or
smtpname option. See the manual page for details.
Some users want to write scripts that take action only if mail could/could not be retrieved, thus fetchmail reports if it has retrieved messages or not.
If you do not want "no mail" to be an error condition (for instance, for cron jobs), use a POSIX-compliant shell and add this to the end of the fetchmail command line, it will change an exit code of 1 to 0 and others to 1:
|| [ $? -eq 1 ]
If you want to map more than one code to 0, you cannot cascade multiple || [ $? -eq N ], but you must instead use the -o operator inside the brackets, (see the test(1) manpage for details), such as:
|| [ $? -eq 1 -o $? -eq 9 ]
A full cron line might then look like this:
*/15 * * * * fetchmail -s || [ $? -eq 1 ]
For most sendmails, no special configuration is required. Eric
Allman tells me that if FEATURE(always_add_domain) is
included in sendmail's configuration, you can leave the
rewrite option off.
If your sendmail complains "sendmail does not relay", make
sure your sendmail.cf file says Cwlocalhost so that
sendmail recognizes 'localhost' as a name of its host.
If you're mailing from another machine on your local network, also ensure that its IP address is listed in ip_allow or name in name_allow (usually in /etc/mail/)
If you find that your sendmail doesn't like the address
'FETCHMAIL-DAEMON@localhost' (which is used in the bouncemail that
fetchmail generates), you may have to set
FEATURE(accept_unqualified_senders).
Günther Leber reports that Digital Unix sendmails won't
work with fetchmail. The symptom is an error message "553
Local configuration error, hostname not recognized as
local". The problem is that fetchmail normally feeds
sendmail with the client machine's host address in the MAIL FROM
line. These sendmails think this means they're seeing the result of
a mail loop and suppress the mail. You may be able to work around
this by running in --invisible mode.
If you want to support multidrop mode, and you can get access to your mailserver's sendmail.cf file, it's a good idea to add this rule:
H?l?Delivered-To: $h
This will cause the mailserver's sendmail to reliably write the appropriate envelope address into each message before fetchmail sees it, and tell fetchmail which header it is. With this change, multidrop mode should work reliably even when the Received header omits the envelope address (which will typically be the case when the message has multiple recipients). However it will still not distinguish the recipients, your only advantage is that no bounce will be sent if a message is BCC addressed to multiple users at your site. To fix even that problem, you might want to try the following hack, which is however untested and quite experimental:
H?J?Delivered-To: $u
Mmdrop, P=/usr/bin/procmail, F=lsDFMqSPfhnu9J,
S=EnvFromSMTP/HdrFromSMTP, R=EnvToSMTP/HdrToSMTP,
T=DNS/RFC822/X-Unix,
A=procmail -Y -a $u -d $h
For both hacks, you have to declare 'envelope
"Delivered-To:"' on the fetchmail side, to put the virtual
domain (e.g. 'domain.com') with RELAY permission into your access
file and to add a line reading 'domain.com
local:local-pop-user' for the first and 'domain.com
mdrop:local-pop-user' for the second hack to your
mailertable.
You will notice that if the mail already has a Delivered-To header, sendmail will not add another. Further, editing sendmail.cf directly is not very comfortable. Solutions for both problems can be found in Peter 'Rattacresh' Backes' 'hybrid' patch against sendmail. Have a look at it, you can find it in the contrib subdirectory.
Feel free to try Martijn Lievaart's detailed recipe in the contrib subdirectory of the fetchmail source distribution, it attempts to realize multidrop mailboxes with an external script.
If for some reason you are invoking sendmail via the mda option (rather than delivering to port 25 via smtp), don't forget to include the -i switch. Otherwise you will occasionally get mysterious delivery failures with a SIGPIPE as the sendmail instance dies. The problem is messages with a single dot at start of a text line.
Avoid qmail, it's broken and unmaintained.
Turn on the forcecr option; qmail's listener mode
doesn't like header or message lines terminated with bare
linefeeds.
(This information contributed by Robert de Bath
<robert@mayday.cix.co.uk>.)
Note that qmail's POP3 server, as of version 1.03 and netqmail 1.05, miscalculates the message sizes, so you may see size-related fetchmail warnings.
If a mailhost is using the qmail package, then it is usually possible to set up one fetchmail link to reliably collect the mail for an entire domain.
One of the basic features of qmail is the 'Delivered-To:' message header. Whenever qmail delivers a message to a local mailbox it puts the username and hostname of the envelope recipient on this line. One major reason for this is to prevent mail loops, the other is to transport envelope information which is essential for multidrop (domain-in-a-mailbox) schemes.
To set up qmail to batch mail for a disconnected site, the ISP-mailhost will have normally put that site in its 'virtualhosts' control file so it will add a prefix to all mail addresses for this site. This results in mail sent to 'username@userhost.userdom.example.com' having a 'Delivered-To:' line of the form:
Delivered-To: mbox-userstr-username@userhost.userdom.example.com
A single host maildrop will be slightly simpler:
Delivered-To: mbox-userstr-username@userhost.example.com
The ISP can make the 'mbox-userstr-' prefix anything they choose but a string matching the user host name is likely.
To use this line you must:
envelope "Delivered-To"' is in the fetchmail
config file.qvirtual "mbox-userstr-"' is
in the fetchmail config file, in order to remove this prefix from the
username. (added by Luca Olivetti)localdomains option containing
'userdom.example.com' or 'userhost.userdom.example.com'
respectively.If you have rewrite on:
There is an RFC1123 requirement that MAIL FROM and RCPT TO addresses you pass to it have to be canonical (e.g. with a fully qualified hostname part). Therefore fetchmail tries to pass fully qualified RCPT TO addresses. But exim does not by default accept 'localhost' as a fully qualified domain. This can be fixed.
In exim.conf, add 'localhost' to your local_domains declaration if it's not already present. For example, the author's site at thyrsus.com would have a line reading:
local_domains = thyrsus.com:localhost
If you have rewrite off:
MAIL FROM is a potential problem if the MTAs upstream from your
fetchmail don't necessarily pass canonicalized From and Return-Path
addresses, and fetchmail's rewrite option is off. The
specific case where this has come up involves bounce messages
generated by sendmail on your mailer host, which have the
(un-canonicalized) origin address MAILER-DAEMON.
The right way to fix this is to enable the rewrite
option and have fetchmail canonicalize From and Return-Path
addresses with the mailserver hostname before exim sees them. This
option is enabled by default, so it won't be off unless you turned
it off.
If you must run with rewrite off, there is a switch
in exim's configuration files that allows it to accept domainless
MAIL FROM addresses; you will have to flip it by putting the
line
sender_unqualified_hosts = localhost
in the main section of the exim configuration file. Note that this will result in such messages having an incorrect domain name attached to their return address (your SMTP listener's hostname rather than that of the remote mail server).
Smail 3.2 is very nearly plug-compatible with sendmail, and may work fine out of the box.
We have one report that when processing multiple messages from a single fetchmail session, smail sometimes delivers them in an order other than received-date order. This can be annoying because it scrambles conversational threads. This is not fetchmail's problem, it is an smail 'feature' and has been reported to the maintainers as a bug.
Very recent smail versions require an
-smtp_hello_verify option in the smail config file.
This overrides smail's check to see that the HELO address is
actually that of the client machine, which is never going to be the
case when fetchmail is in the picture. According to RFC1123 an SMTP
listener must allow this mismatch, so smail's new behavior
(introduced sometime between 3.2.0.90 and 3.2.0.95) is a bug.
You may also need to say
-smtp_hello_broken_allow=127.0.0.1 in order for smail
to accept the "localhost" that fetchmail normally appends to
recipient addresses.
MMDF itself is difficult to configure, but it turns out that connecting fetchmail to MMDF's SMTP channel isn't that hard. You can read an MMDF recipe that describes replacing a UUCP link with fetchmail feeding MMDF.
The Lotus Notes SMTP gateway tries to deduce when it should convert \n to \r\n, but its rules are not the intuitive and correct-for-RFC822 ones. Use 'forcecr'.
The courier mta doesn't like RCPT addresses that look like
someone@localhost. Work around this with an
smtphost or smtpaddress.
vbmailshield's SMTP interpreter is broken. It doesn't understand RSET.
As a workaround, you can set batchlimit to 1 so RSET is never used.
The information that used to be here was obsolete and dropped.
It's been reliably reported that Exchange 2000's POP3 support is so broken that it's unusable. One symptom is that messages without a terminating newline get the POP3 message termination dot emitted -- you guessed it -- right after the last character of the message, with no terminating newline added. This will hang fetchmail or any other RFC-compliant server. IMAP is alleged to work OK, though.
Older versions of Exchange are semi-usable. They randomly drop attachments on the floor, though. Microsoft acknowledges this as a known bug and apparently has no plans to fix it.
Fetchmail using IMAP usually supports the proprietary NTLM mode used with Microsoft Exchange servers. "Usually" here means that it fails on some servers for reasons that we haven't been able to debug yet, perhaps it's related to the NTLM domain.
To enable this NTLM mode, configure fetchmail with the --enable-NTLM option and recompile it. Specify a user option value that looks like 'user@domain': the part to the left of the @ will be passed as the username and the part to the right as the NTLM domain.
Microsoft Exchange violates the POP3 and IMAP RFCs. Its LIST command does not reveal the real sizes of mail in the pop mailbox, but the sizes of the compressed versions in the exchange mail database (thanks to Arjan De Vet and Guido Van Rooij for alerting us to this problem).
Fetchmail works with Microsoft Exchange, despite this brain damage. Two features are compromised. One is that the --limit option will not work right (it will check against compressed and not actual sizes). The other is that a too-small SIZE argument may be passed to your ESMTP listener, assuming you're using one (this should not be a problem unless the actual size of the message is above the listener's configured length limit).
ESR learned that there's supposed to be a registry bit that can fix this breakage:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MsExchangeIs\Parameters System\Pop3 Compatibility
This is a bitmask that controls the variations from the standard protocol. The bits defined are:
There's another one that may be useful to know about:
KEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MsExchangeIs\Parameters System\Pop3 Performance
The Microsoft employee who revealed this information to ESR admitted that he couldn't find it anywhere in their public knowledge base.
Another specific problem we have seen with Exchange servers has as its symptom a response to LOGIN that says "NO Ambiguous Alias". Grant Edwards writes:
This means that Exchange Server is too [...] stupid to figure out which mailbox belongs to you. Instead of actually keeping track of which inbox belongs to which user, it uses some half-witted, guess-o-matic heuristic to try to guess your mailbox name from your username.
In your case it doesn't work because your username maps to more than one mailbox. For some people it doesn't work because their username maps to zero mailboxes.
You've got several options:
- Get your administrator to configure the server so that usernames and mailbox names are the same.
- Get your administrator to add an alias that maps your username explicitly to your mailbox name.
But, the best option involves finding a server that runs better software.
No special configuration is required, but OpenMail versions prior to 6.0 have an annoying bug similar to the big one in Microsoft Exchange. The message sizes it gives in the LIST are rounded to the nearest 1024 bytes. It also has a nasty habit of discarding headers it doesn't recognize, such as X- and Resent- headers.
OpenMail's project manager claims these bugs have been fixed in 6.0.
We've had a more recent report (December 2001) that the TOP command fails, returning only one line regardless of its argument, on something identifying itself as "OpenMail POP3 interface".
The Novell GroupWise IMAP server is (according to the designer of IMAP) unusably broken. Among other things, it doesn't include a required content length in its BODY[TEXT] response.
Fetchmail works around this problem to some extent, but no guarantees.
You can't. At least not if you want to be able to see attachments. InterChange has a bug similar to the MailMax server (see below): it reports the message length with attachments but doesn't download them on TOP or RETR.
On Jan 9 2001, the people at InfiniteMail sent ESR mail informing him that their new 3.61.08 release of InterChange fixed this problem.
You can't. At least not if you want to be able to see attachments. MailMax has a bug; it reports the message length with attachments but doesn't download them on TOP or RETR.
Also, we're told that TOP sometimes fails to retrieve the entire message even when enough lines have been specified. The MailMax developers have acknowledged this bug as of 4 May 2000, but there is no fix yet. If you must use this server, force RETR with the fetchall option.
The FTGate V2 server (and possibly older versions as well) has a
weird bug. It answers OK twice to a TOP request! Use the
fetchall option to force use of RETR and work around
this bug.
First, make sure your fetchmail has the RPA support compiled in.
Stock fetchmail binaries (such as you might get from an RPM) don't.
You can check this by looking at the output of fetchmail
-V; if you see the string "+RPA" after the version ID you're
good to go, otherwise you'll have to build your own from sources
(see the INSTALL file in the source distribution for
directions).
Give your CompuServe pass-phrase in lower case as your password. Add '@compuserve.com' to your user ID so that it looks like 'user <UserID>@compuserve.com', where <UserID> can be either your numerical userID or your E-mail nickname. An RPA-enabled fetchmail will automatically check for csi.com in the POP server's greeting line. If that's found, and your user ID ends with '@compuserve.com', it will query the server to see if it is RPA-capable, and if so do an RPA transaction rather than a plain-text password handshake.
Warning: the debug (-v -v) output of fetchmail will show your pass-phrase in Unicode!
These two .fetchmailrc entries show the difference between an RPA and non-RPA configuration:
# This version will use RPA
poll csi.com via "pop.site1.csi.com" with proto POP3 and options no dns
user "CSERVE_USER@compuserve.com" there with password "CSERVE_PASSWORD"
is LOCAL_USER here options fetchall stripcr
# This version will not use RPA
poll non-rpa.csi.com via "pop.site1.csi.com" with proto POP3 and options no dns
user "CSERVE_USER" there with password "CSERVE_POP3_PASSWORD"
is LOCAL_USER here options fetchall stripcr
You can get fetchmail to download the email for just one user from Demon Internet's POP3 server by giving it a username consisting of your Demon user name followed by your account name, with an at-sign between them.
For example, to download email for the user <philh@vision25.demon.co.uk>, you could use the following .fetchmailrc file:
set postmaster "philh"
poll pop3.demon.co.uk with protocol POP3:
user "philh@vision25" is philh
Demon Internet's SDPS service is an implementation of POP3. All messages have a Received: header added when they enter the maildrop, like this:
Received: from punt-1.mail.demon.net by mailstore for fred@xyz.demon.co.uk
id 899963657:10:27896:0; Thu, 09 Jul 98 05:54:17 GMT
To enable multi-drop mode you need to tell fetchmail that 'mailstore' is the name of the host which accepted the mail, and let it know the hostname part(s) of your E-mail address. The following example assumes that your hostname is xyz.demon.co.uk, and that you have also bought "mail forwarding" for the domain my-company.co.uk (in which case your MTA must also be configured to accept mail sent to user@my-company.co.uk)
poll pop3.demon.co.uk proto pop3 aka mailstore no dns:
localdomains xyz.demon.co.uk my-company.co.uk
user xyz is *
Note that Demon may delete mail on the server which is more than 30 days old; see their POP3 page for details.
There's a different way to do multidrop. It's not necessary on Demon Internet, since fetchmail can parse Received addresses, but the person who implemented this didn't know that. It may be useful if Demon Internet ever changes mail transports.
SDPS includes a non-standard extension for retrieving the envelope of a message (*ENV), which fetchmail optionally supports if compiled with the --enable-SDPS option. If you have it, the first line of the fetchmail -V response will include the string "+SDPS".
Once you have SDPS compiled in, fetchmail in POP3 mode will automatically detect when it's talking to a Demon Internet host in multidrop mode, and use the *ENV extension to get an envelope To address.
The autodetection works by looking at the hostname in the POP3 greeting line; if you're accessing Demon Internet through a proxy it may fail. To force SDPS mode, pick "sdps" as your protocol.
Enable 'fetchall'. A user reports that the 2.2
version of USA.NET's POP server reports that you must use the
'fetchall' option to make sure that all of the mail is
retrieved, otherwise some may be left on the server. This is almost
certainly a server bug.
The usa.net servers (at least in their 2.2 version, June 1998)
don't handle the TOP command properly, either. Regardless of the
argument you give it, they retrieve only about 10 lines of the
message. Fetchmail normally uses TOP for message retrieval in order
to avoid marking messages seen, but 'fetchall' forces
it to use RETR instead.
Also, we're told USA.NET adds a ton of hops to your messages. You may need to raise the MaxHopCount parameter in your sendmail.cf to avoid having fetched mail rejected.
Nathan Cutler reports that the the mail.geocities.com POP3 servers fail to include the first Received line of the message in the send to fetchmail. This can solve problems if your MUA interprets Received continuations as body lines and doesn't parse any of the following headers.
Workaround is to use "mda" keyword or "--mda" switch:
mda "sed -e '1s/^\t/Received: /' | formail | /usr/bin/procmail -d <user>"
Replace \t with exactly one tabulation character.
You should also consider using "fetchall" option because Geocities' servers sometimes think that the first 45 messages have already been read.
You can't directly. But you can use fetchmail with hotmail or lycos webmail with the help of the HotWayDaemon daemon. You don't even need to install hotwayd as a daemon in inetd.conf but can use it as a plugin. Your configuration should look like this:
poll localhost protocol pop3 tracepolls plugin "/usr/local/sbin/hotwayd -l 0 -p yourproxy:yourproxyport" username "youremail@hotmail.com" password "yourpassword" fetchall
As a second option you may consider using gotmail.
You can't. MSN uses something that looks like POP3, except the authentication part is nonstandard. And of course they don't document it, so nobody but their Windows clients can speak it.
This is a customer lock-in tactic; we recommend boycotting MSN as the only appropriate response.
As of 5.0.8, we have support for the client side of NTLM authentication. It's possible this may enable fetchmail to talk to MSN; if so, somebody should report it so this FAQ can be corrected.
The SpryNet POP3 servers mark a message queried with TOP as
seen. This means that if your connection drops in mid-message, it
may end up invisibly stuck on your mail spool. Use the
fetchall flag to ensure that it's recovered on the
next cycle.
Stock fetchmail will work with a Maillennium POP3/PROXY server... but this server will truncate "TOP" responses after 64 - 82 kB (we have varying reports), in violation of Internet Standard #53 aka. RFC-1939 (POP3). Don't mistake this for a fetchmail bug. (Reported July 2003.) Comcast documented they haven't understood what this is about in two messages from April 2004.
Beginning with version 6.3.2, fetchmail will fall back to the RETR command if the greeting string contains "Maillennium POP3/PROXY server", and print a warning message. This means however that fetchmail has no means to prevent the "seen" flag from being set on the server (Note that officially, POP3 has no notion of seen tracking, but it works for some sites.)
Workaround for older versions: use the fetchall option.
Google's IMAP servers, as of April 2008, are broken and re-encode MIME-encoded headers improperly and are not feature-complete yet. The model how their servers organize mail also deviates in significant ways from what the POP3 or IMAP protocol 'fathers' conceived. This means all sorts of strange effects, for instance, your sent mail may show up in the mail that fetchmail fetches. It's best to avoid fetching mail from Google until they are using standards-compliant software.
Giuseppe Guerini added a --with-socks compile-time option that supports linking with socks library. If you specify the value of this option as "yes", the configure script will try to find the Rconnect library and set the makefile up to link it. You can also specify a directory containing the Rconnect library.
Alan Schmitt has added a similar --with-socks5 option that may work better if you have a recent version of the SOCKS library.
In either case, fetchmail has no direct configuration hooks, but you can specify which socks configuration file the library should read by means of the SOCKS_CONF environment variable. In order to bypass the SOCKS proxy altogether, you could run (adding your usual options to the end of this line):
env SOCKS_CONF=/dev/null fetchmail
To use fetchmail with IPv6, you need a system that supports IPv6, the "Basic Socket Interface Extensions for IPv6" (RFC 2133).
The NRL IPv6+IPsec software distribution can be obtained from: http://web.mit.edu/network/isakmp/
More information on using IPv6 with Linux can be obtained from:
Use the plugin option. This is dead simple with IMAP:
plugin "ssh %h /usr/sbin/imapd"
You may have to use a different absolute pathname, whatever the location of imapd on your mailserver is. This option tells fetchmail that instead of opening a connection on the server's port 143 and doing standard IMAP authentication, fetchmail should ssh to the server and run imapd, using the more secure ssh authentication (as well as getting ssh's end-to-end encryption). Most IMAP daemons will detect that they've been called from the command line and assume the connection is preauthenticated.
POP3 daemons aren't quite as smart. They won't know they are preauthenticated in this mode, so you'll actually have to ship your password. It will be under ssh encryption, though, so that shouldn't be a problem.
Fetchmail can use RFC1731 GSSAPI authorization to safely identify you to your IMAP server, as long as you can share Kerberos V credentials with your mail host and you have a GSSAPI-capable IMAP server.
fetchmail does not compile in support for GSS by default, since it requires libraries from a Kerberos V distribution, such as MIT Kerberos or Heimdal Kerberos.
If you have these, compiling in GSS support is simple: add a
--with-gssapi=[/path/to/krb5/root] option to
configure. For instance, I have all of my Kerberos V libraries
installed under /usr/krb5 so I run configure
--with-gssapi=/usr/krb5
Setting up Kerberos V authentication is beyond the scope of this FAQ (you may find Jim Rome's paper How to Kerberize your site helpful), but you'll at least need to add a credential for imap/[mailhost] to the keytab of the mail server (IMAP doesn't just use the host key). Then you'll need to have your credentials ready on your machine (cf. kinit).
After that things are very simple. Set your protocol to imap-gss in your .fetchmailrc, and omit the password, since imap-gss doesn't need one. You can specify a username if you want, but this is only useful if your mailbox belongs to a username different from your Kerberos principal.
Now you don't have to worry about your password appearing in cleartext in your .fetchmailrc, or across the network.
You'll need to have the OpenSSL libraries installed, and they should at least be version 0.9.7. Configure with --with-ssl. If you have the OpenSSL libraries installed in commonly-used default locations, this will suffice. If you have them installed in a non-default location, you'll need to specify the OpenSSL installation directory as an argument to --with-ssl after an equal sign.
Fetchmail binaries built this way support ssl,
sslkey, and sslcert options that control
SSL encryption, and will automatically use tls if the
server offers it. You will need to have an SSL-enabled mailserver to
use these options. See the manual page for details and some words
of care on the limited security provided.
If your open OpenSSL session dies with a message that complains "PRNG not seeded", update or improve your operating system. This means that the OpenSSL library on your machine has been unable to locate a source of random bits from which to seed its random-number generator; normally these come from the /dev/urandom, and this message probably means your OS doesn't have that device.
An interactive program could seed the random number generator from keystroke timings or some other form of user input. Because fetchmail is primarily designed to run forever as a background daemon, that option is not available in this case.
If you don't have the libraries installed, but do have the OpenSSL utility toolkit, something like this may work (but will not authenticate the server):
poll MYSERVER port 993 plugin "openssl s_client -connect %h:%p"
protocol imap username MYUSERNAME password MYPASSWORD
You should note that SSL is only secure against a "man-in-the-middle" attack if the client is able to verify that the peer's public key is the correct one, and has not been substituted by an attacker. fetchmail can do this in one of two ways: by verifying the SSL certificate, or by checking the fingerprint of the peer's public key.
There are three parts to SSL certificate verification: checking that the domain name in the certificate matches the hostname you asked to connect to; checking that the certificate expiry date has not passed; and checking that the certificate has been signed by a known Certificate Authority (CA). This last step takes some preparation, as you need to install the root certificates of all the CA's which you might come across.
The easiest way to do this is using the root CA keys supplied in the OpenSSL distribution, which means you need to download and unpack the source tarball from www.openssl.org. Once you have done that:
mkdir /etc/ssl/certscp *.pem /etc/ssl/certs/$dir="/etc/ssl"Now in .fetchmailrc, set option sslcertpath to point to this directory:
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslcertpath /etc/ssl/certs
If the server certificate has not been signed by a known CA (e.g. it is a self-signed certificate), then this certificate validation will always fail.
Certificate verification is always attempted. If it fails, by default a warning is printed but the connection carries on (which means you are not protected against attack). If your server's certificate has been properly set up and verifies correctly, then add the "sslcertck" option to enforce validation. If your server doesn't have a valid certificate though (e.g. it has a self-signed certificate) then it will never verify, and the only way you can protect yourself is by checking the fingerprint.
To check the peer fingerprint: first use fetchmail -v once to connect to the host, at a time when you are pretty sure that there is no attack in progress (e.g. you are not traversing any untrusted network to reach the server). Make a note of the fingerprint shown. Now embed this in your .fetchmailrc using the sslfingerprint option: e.g.
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslfingerprint "67:3E:02:94:D3:5B:C3:16:86:71:37:01:B1:3B:BC:E2"
When you next connect, the public key presented by the server will be verified against the fingerprint given. If it's different, it may mean that a man-in-the-middle attack is in progress - or it might just mean that the server changed its key. It's up to you to determine which has happened.
Some servers advertise STLS (POP3) or STARTTLS (IMAP), and fetchmail will automatically attempt TLS negotiation if SSL was enabled at compile time. This can however cause problems if the upstream didn't configure his certificates properly.
In order to prevent fetchmail from trying TLS (STLS, STARTTLS) negotiation, add this option:
sslproto ssl23
This restricts fetchmail's SSL/TLS protocol choice from the default "SSLv2, SSLv3, TLSv1" to the two SSL variants, disabling TLSv1. Note however that this causes the connection to be unencrypted unless an encrypting "plugin" is used or SSL is requested explicitly.
Fetchmail itself is probably working, but your SMTP port 25 listener is down or inaccessible.
The first thing to check is if you can telnet to port 25 on your smtp host (which is normally 'localhost' unless you've specified an smtp option in your .fetchmailrc or on the command line) and get a greeting line from the listener. If the SMTP host is inaccessible or the listener is down, fix that first.
In Red Hat Linux 6.x, SMTP is disabled by default. To fix this, set "DAEMON=yes" in your /etc/sys (STLShey are preauthenticated in this mode, so you'll actually have to ship your password. It will be under ssh encryption, though, so that shouldn't be a problem.
Fetchmail can use RFC1731 GSSAPI authorization to safely identify you to your IMAP server, as long as you can share Kerberos V credentials with your mail host and you have a GSSAPI-capable IMAP server.
fetchmail does not compile in support for GSS by default, since it requires libraries from a Kerberos V distribution, such as MIT Kerberos or Heimdal Kerberos.
If you have these, compiling in GSS support is simple: add a
--with-gssapi=[/path/to/krb5/root] option to
configure. For instance, I have all of my Kerberos V libraries
installed under /usr/krb5 so I run configure
--with-gssapi=/usr/krb5
Setting up Kerberos V authentication is beyond the scope of this FAQ (you may find Jim Rome's paper How to Kerberize your site helpful), but you'll at least need to add a credential for imap/[mailhost] to the keytab of the mail server (IMAP doesn't just use the host key). Then you'll need to have your credentials ready on your machine (cf. kinit).
After that things are very simple. Set your protocol to imap-gss in your .fetchmailrc, and omit the password, since imap-gss doesn't need one. You can specify a username if you want, but this is only useful if your mailbox belongs to a username different from your Kerberos principal.
Now you don't have to worry about your password appearing in cleartext in your .fetchmailrc, or across the network.
You'll need to have the OpenSSL libraries installed, and they should at least be version 0.9.7. Configure with --with-ssl. If you have the OpenSSL libraries installed in commonly-used default locations, this will suffice. If you have them installed in a non-default location, you'll need to specify the OpenSSL installation directory as an argument to --with-ssl after an equal sign.
Fetchmail binaries built this way support ssl,
sslkey, and sslcert options that control
SSL encryption, and will automatically use tls if the
server offers it. You will need to have an SSL-enabled mailserver to
use these options. See the manual page for details and some words
of care on the limited security provided.
If your open OpenSSL session dies with a message that complains "PRNG not seeded", update or improve your operating system. This means that the OpenSSL library on your machine has been unable to locate a source of random bits from which to seed its random-number generator; normally these come from the /dev/urandom, and this message probably means your OS doesn't have that device.
An interactive program could seed the random number generator from keystroke timings or some other form of user input. Because fetchmail is primarily designed to run forever as a background daemon, that option is not available in this case.
If you don't have the libraries installed, but do have the OpenSSL utility toolkit, something like this may work (but will not authenticate the server):
poll MYSERVER port 993 plugin "openssl s_client -connect %h:%p"
protocol imap username MYUSERNAME password MYPASSWORD
You should note that SSL is only secure against a "man-in-the-middle" attack if the client is able to verify that the peer's public key is the correct one, and has not been substituted by an attacker. fetchmail can do this in one of two ways: by verifying the SSL certificate, or by checking the fingerprint of the peer's public key.
There are three parts to SSL certificate verification: checking that the domain name in the certificate matches the hostname you asked to connect to; checking that the certificate expiry date has not passed; and checking that the certificate has been signed by a known Certificate Authority (CA). This last step takes some preparation, as you need to install the root certificates of all the CA's which you might come across.
The easiest way to do this is using the root CA keys supplied in the OpenSSL distribution, which means you need to download and unpack the source tarball from www.openssl.org. Once you have done that:
mkdir /etc/ssl/certscp *.pem /etc/ssl/certs/$dir="/etc/ssl"Now in .fetchmailrc, set option sslcertpath to point to this directory:
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslcertpath /etc/ssl/certs
If the server certificate has not been signed by a known CA (e.g. it is a self-signed certificate), then this certificate validation will always fail.
Certificate verification is always attempted. If it fails, by default a warning is printed but the connection carries on (which means you are not protected against attack). If your server's certificate has been properly set up and verifies correctly, then add the "sslcertck" option to enforce validation. If your server doesn't have a valid certificate though (e.g. it has a self-signed certificate) then it will never verify, and the only way you can protect yourself is by checking the fingerprint.
To check the peer fingerprint: first use fetchmail -v once to connect to the host, at a time when you are pretty sure that there is no attack in progress (e.g. you are not traversing any untrusted network to reach the server). Make a note of the fingerprint shown. Now embed this in your .fetchmailrc using the sslfingerprint option: e.g.
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslfingerprint "67:3E:02:94:D3:5B:C3:16:86:71:37:01:B1:3B:BC:E2"
When you next connect, the public key presented by the server will be verified against the fingerprint given. If it's different, it may mean that a man-in-the-middle attack is in progress - or it might just mean that the server changed its key. It's up to you to determine which has happened.
Some servers advertise STLS (POP3) or STARTTLS (IMAP), and fetchmail will automatically attempt TLS negotiation if SSL was enabled at compile time. This can however cause problems if the upstream didn't configure his certificates properly.
In order to prevent fetchmail from trying TLS (STLS, STARTTLS) negotiation, add this option:
sslproto ssl23
This restricts fetchmail's SSL/TLS protocol choice from the default "SSLv2, SSLv3, TLSv1" to the two SSL variants, disabling TLSv1. Note however that this causes the connection to be unencrypted unless an encrypting "plugin" is used or SSL is requested explicitly.
Fetchmail itself is probably working, but your SMTP port 25 listener is down or inaccessible.
The first thing to check is if you can telnet to port 25 on your smtp host (which is normally 'localhost' unless you've specified an smtp option in your .fetchmailrc or on the command line) and get a greeting line from the listener. If the SMTP host is inaccessible or the listener is down, fix that first.
In Red Hat Linux 6.x, SMTP is disabled by default. To fix this, set "DAEMON=yes" in your /etc/sys (STLShey are preauthenticated in this mode, so you'll actually have to ship your password. It will be under ssh encryption, though, so that shouldn't be a problem.
Fetchmail can use RFC1731 GSSAPI authorization to safely identify you to your IMAP server, as long as you can share Kerberos V credentials with your mail host and you have a GSSAPI-capable IMAP server.
fetchmail does not compile in support for GSS by default, since it requires libraries from a Kerberos V distribution, such as MIT Kerberos or Heimdal Kerberos.
If you have these, compiling in GSS support is simple: add a
--with-gssapi=[/path/to/krb5/root] option to
configure. For instance, I have all of my Kerberos V libraries
installed under /usr/krb5 so I run configure
--with-gssapi=/usr/krb5
Setting up Kerberos V authentication is beyond the scope of this FAQ (you may find Jim Rome's paper How to Kerberize your site helpful), but you'll at least need to add a credential for imap/[mailhost] to the keytab of the mail server (IMAP doesn't just use the host key). Then you'll need to have your credentials ready on your machine (cf. kinit).
After that things are very simple. Set your protocol to imap-gss in your .fetchmailrc, and omit the password, since imap-gss doesn't need one. You can specify a username if you want, but this is only useful if your mailbox belongs to a username different from your Kerberos principal.
Now you don't have to worry about your password appearing in cleartext in your .fetchmailrc, or across the network.
You'll need to have the OpenSSL libraries installed, and they should at least be version 0.9.7. Configure with --with-ssl. If you have the OpenSSL libraries installed in commonly-used default locations, this will suffice. If you have them installed in a non-default location, you'll need to specify the OpenSSL installation directory as an argument to --with-ssl after an equal sign.
Fetchmail binaries built this way support ssl,
sslkey, and sslcert options that control
SSL encryption, and will automatically use tls if the
server offers it. You will need to have an SSL-enabled mailserver to
use these options. See the manual page for details and some words
of care on the limited security provided.
If your open OpenSSL session dies with a message that complains "PRNG not seeded", update or improve your operating system. This means that the OpenSSL library on your machine has been unable to locate a source of random bits from which to seed its random-number generator; normally these come from the /dev/urandom, and this message probably means your OS doesn't have that device.
An interactive program could seed the random number generator from keystroke timings or some other form of user input. Because fetchmail is primarily designed to run forever as a background daemon, that option is not available in this case.
If you don't have the libraries installed, but do have the OpenSSL utility toolkit, something like this may work (but will not authenticate the server):
poll MYSERVER port 993 plugin "openssl s_client -connect %h:%p"
protocol imap username MYUSERNAME password MYPASSWORD
You should note that SSL is only secure against a "man-in-the-middle" attack if the client is able to verify that the peer's public key is the correct one, and has not been substituted by an attacker. fetchmail can do this in one of two ways: by verifying the SSL certificate, or by checking the fingerprint of the peer's public key.
There are three parts to SSL certificate verification: checking that the domain name in the certificate matches the hostname you asked to connect to; checking that the certificate expiry date has not passed; and checking that the certificate has been signed by a known Certificate Authority (CA). This last step takes some preparation, as you need to install the root certificates of all the CA's which you might come across.
The easiest way to do this is using the root CA keys supplied in the OpenSSL distribution, which means you need to download and unpack the source tarball from www.openssl.org. Once you have done that:
mkdir /etc/ssl/certscp *.pem /etc/ssl/certs/$dir="/etc/ssl"Now in .fetchmailrc, set option sslcertpath to point to this directory:
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslcertpath /etc/ssl/certs
If the server certificate has not been signed by a known CA (e.g. it is a self-signed certificate), then this certificate validation will always fail.
Certificate verification is always attempted. If it fails, by default a warning is printed but the connection carries on (which means you are not protected against attack). If your server's certificate has been properly set up and verifies correctly, then add the "sslcertck" option to enforce validation. If your server doesn't have a valid certificate though (e.g. it has a self-signed certificate) then it will never verify, and the only way you can protect yourself is by checking the fingerprint.
To check the peer fingerprint: first use fetchmail -v once to connect to the host, at a time when you are pretty sure that there is no attack in progress (e.g. you are not traversing any untrusted network to reach the server). Make a note of the fingerprint shown. Now embed this in your .fetchmailrc using the sslfingerprint option: e.g.
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslfingerprint "67:3E:02:94:D3:5B:C3:16:86:71:37:01:B1:3B:BC:E2"
When you next connect, the public key presented by the server will be verified against the fingerprint given. If it's different, it may mean that a man-in-the-middle attack is in progress - or it might just mean that the server changed its key. It's up to you to determine which has happened.
Some servers advertise STLS (POP3) or STARTTLS (IMAP), and fetchmail will automatically attempt TLS negotiation if SSL was enabled at compile time. This can however cause problems if the upstream didn't configure his certificates properly.
In order to prevent fetchmail from trying TLS (STLS, STARTTLS) negotiation, add this option:
sslproto ssl23
This restricts fetchmail's SSL/TLS protocol choice from the default "SSLv2, SSLv3, TLSv1" to the two SSL variants, disabling TLSv1. Note however that this causes the connection to be unencrypted unless an encrypting "plugin" is used or SSL is requested explicitly.
Fetchmail itself is probably working, but your SMTP port 25 listener is down or inaccessible.
The first thing to check is if you can telnet to port 25 on your smtp host (which is normally 'localhost' unless you've specified an smtp option in your .fetchmailrc or on the command line) and get a greeting line from the listener. If the SMTP host is inaccessible or the listener is down, fix that first.
In Red Hat Linux 6.x, SMTP is disabled by default. To fix this, set "DAEMON=yes" in your /etc/sys (STLShey are preauthenticated in this mode, so you'll actually have to ship your password. It will be under ssh encryption, though, so that shouldn't be a problem.
Fetchmail can use RFC1731 GSSAPI authorization to safely identify you to your IMAP server, as long as you can share Kerberos V credentials with your mail host and you have a GSSAPI-capable IMAP server.
fetchmail does not compile in support for GSS by default, since it requires libraries from a Kerberos V distribution, such as MIT Kerberos or Heimdal Kerberos.
If you have these, compiling in GSS support is simple: add a
--with-gssapi=[/path/to/krb5/root] option to
configure. For instance, I have all of my Kerberos V libraries
installed under /usr/krb5 so I run configure
--with-gssapi=/usr/krb5
Setting up Kerberos V authentication is beyond the scope of this FAQ (you may find Jim Rome's paper How to Kerberize your site helpful), but you'll at least need to add a credential for imap/[mailhost] to the keytab of the mail server (IMAP doesn't just use the host key). Then you'll need to have your credentials ready on your machine (cf. kinit).
After that things are very simple. Set your protocol to imap-gss in your .fetchmailrc, and omit the password, since imap-gss doesn't need one. You can specify a username if you want, but this is only useful if your mailbox belongs to a username different from your Kerberos principal.
Now you don't have to worry about your password appearing in cleartext in your .fetchmailrc, or across the network.
You'll need to have the OpenSSL libraries installed, and they should at least be version 0.9.7. Configure with --with-ssl. If you have the OpenSSL libraries installed in commonly-used default locations, this will suffice. If you have them installed in a non-default location, you'll need to specify the OpenSSL installation directory as an argument to --with-ssl after an equal sign.
Fetchmail binaries built this way support ssl,
sslkey, and sslcert options that control
SSL encryption, and will automatically use tls if the
server offers it. You will need to have an SSL-enabled mailserver to
use these options. See the manual page for details and some words
of care on the limited security provided.
If your open OpenSSL session dies with a message that complains "PRNG not seeded", update or improve your operating system. This means that the OpenSSL library on your machine has been unable to locate a source of random bits from which to seed its random-number generator; normally these come from the /dev/urandom, and this message probably means your OS doesn't have that device.
An interactive program could seed the random number generator from keystroke timings or some other form of user input. Because fetchmail is primarily designed to run forever as a background daemon, that option is not available in this case.
If you don't have the libraries installed, but do have the OpenSSL utility toolkit, something like this may work (but will not authenticate the server):
poll MYSERVER port 993 plugin "openssl s_client -connect %h:%p"
protocol imap username MYUSERNAME password MYPASSWORD
You should note that SSL is only secure against a "man-in-the-middle" attack if the client is able to verify that the peer's public key is the correct one, and has not been substituted by an attacker. fetchmail can do this in one of two ways: by verifying the SSL certificate, or by checking the fingerprint of the peer's public key.
There are three parts to SSL certificate verification: checking that the domain name in the certificate matches the hostname you asked to connect to; checking that the certificate expiry date has not passed; and checking that the certificate has been signed by a known Certificate Authority (CA). This last step takes some preparation, as you need to install the root certificates of all the CA's which you might come across.
The easiest way to do this is using the root CA keys supplied in the OpenSSL distribution, which means you need to download and unpack the source tarball from www.openssl.org. Once you have done that:
mkdir /etc/ssl/certscp *.pem /etc/ssl/certs/$dir="/etc/ssl"Now in .fetchmailrc, set option sslcertpath to point to this directory:
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslcertpath /etc/ssl/certs
If the server certificate has not been signed by a known CA (e.g. it is a self-signed certificate), then this certificate validation will always fail.
Certificate verification is always attempted. If it fails, by default a warning is printed but the connection carries on (which means you are not protected against attack). If your server's certificate has been properly set up and verifies correctly, then add the "sslcertck" option to enforce validation. If your server doesn't have a valid certificate though (e.g. it has a self-signed certificate) then it will never verify, and the only way you can protect yourself is by checking the fingerprint.
To check the peer fingerprint: first use fetchmail -v once to connect to the host, at a time when you are pretty sure that there is no attack in progress (e.g. you are not traversing any untrusted network to reach the server). Make a note of the fingerprint shown. Now embed this in your .fetchmailrc using the sslfingerprint option: e.g.
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslfingerprint "67:3E:02:94:D3:5B:C3:16:86:71:37:01:B1:3B:BC:E2"
When you next connect, the public key presented by the server will be verified against the fingerprint given. If it's different, it may mean that a man-in-the-middle attack is in progress - or it might just mean that the server changed its key. It's up to you to determine which has happened.
Some servers advertise STLS (POP3) or STARTTLS (IMAP), and fetchmail will automatically attempt TLS negotiation if SSL was enabled at compile time. This can however cause problems if the upstream didn't configure his certificates properly.
In order to prevent fetchmail from trying TLS (STLS, STARTTLS) negotiation, add this option:
sslproto ssl23
This restricts fetchmail's SSL/TLS protocol choice from the default "SSLv2, SSLv3, TLSv1" to the two SSL variants, disabling TLSv1. Note however that this causes the connection to be unencrypted unless an encrypting "plugin" is used or SSL is requested explicitly.
Fetchmail itself is probably working, but your SMTP port 25 listener is down or inaccessible.
The first thing to check is if you can telnet to port 25 on your smtp host (which is normally 'localhost' unless you've specified an smtp option in your .fetchmailrc or on the command line) and get a greeting line from the listener. If the SMTP host is inaccessible or the listener is down, fix that first.
In Red Hat Linux 6.x, SMTP is disabled by default. To fix this, set "DAEMON=yes" in your /etc/sys (STLShey are preauthenticated in this mode, so you'll actually have to ship your password. It will be under ssh encryption, though, so that shouldn't be a problem.
Fetchmail can use RFC1731 GSSAPI authorization to safely identify you to your IMAP server, as long as you can share Kerberos V credentials with your mail host and you have a GSSAPI-capable IMAP server.
fetchmail does not compile in support for GSS by default, since it requires libraries from a Kerberos V distribution, such as MIT Kerberos or Heimdal Kerberos.
If you have these, compiling in GSS support is simple: add a
--with-gssapi=[/path/to/krb5/root] option to
configure. For instance, I have all of my Kerberos V libraries
installed under /usr/krb5 so I run configure
--with-gssapi=/usr/krb5
Setting up Kerberos V authentication is beyond the scope of this FAQ (you may find Jim Rome's paper How to Kerberize your site helpful), but you'll at least need to add a credential for imap/[mailhost] to the keytab of the mail server (IMAP doesn't just use the host key). Then you'll need to have your credentials ready on your machine (cf. kinit).
After that things are very simple. Set your protocol to imap-gss in your .fetchmailrc, and omit the password, since imap-gss doesn't need one. You can specify a username if you want, but this is only useful if your mailbox belongs to a username different from your Kerberos principal.
Now you don't have to worry about your password appearing in cleartext in your .fetchmailrc, or across the network.
You'll need to have the OpenSSL libraries installed, and they should at least be version 0.9.7. Configure with --with-ssl. If you have the OpenSSL libraries installed in commonly-used default locations, this will suffice. If you have them installed in a non-default location, you'll need to specify the OpenSSL installation directory as an argument to --with-ssl after an equal sign.
Fetchmail binaries built this way support ssl,
sslkey, and sslcert options that control
SSL encryption, and will automatically use tls if the
server offers it. You will need to have an SSL-enabled mailserver to
use these options. See the manual page for details and some words
of care on the limited security provided.
If your open OpenSSL session dies with a message that complains "PRNG not seeded", update or improve your operating system. This means that the OpenSSL library on your machine has been unable to locate a source of random bits from which to seed its random-number generator; normally these come from the /dev/urandom, and this message probably means your OS doesn't have that device.
An interactive program could seed the random number generator from keystroke timings or some other form of user input. Because fetchmail is primarily designed to run forever as a background daemon, that option is not available in this case.
If you don't have the libraries installed, but do have the OpenSSL utility toolkit, something like this may work (but will not authenticate the server):
poll MYSERVER port 993 plugin "openssl s_client -connect %h:%p"
protocol imap username MYUSERNAME password MYPASSWORD
You should note that SSL is only secure against a "man-in-the-middle" attack if the client is able to verify that the peer's public key is the correct one, and has not been substituted by an attacker. fetchmail can do this in one of two ways: by verifying the SSL certificate, or by checking the fingerprint of the peer's public key.
There are three parts to SSL certificate verification: checking that the domain name in the certificate matches the hostname you asked to connect to; checking that the certificate expiry date has not passed; and checking that the certificate has been signed by a known Certificate Authority (CA). This last step takes some preparation, as you need to install the root certificates of all the CA's which you might come across.
The easiest way to do this is using the root CA keys supplied in the OpenSSL distribution, which means you need to download and unpack the source tarball from www.openssl.org. Once you have done that:
mkdir /etc/ssl/certscp *.pem /etc/ssl/certs/$dir="/etc/ssl"Now in .fetchmailrc, set option sslcertpath to point to this directory:
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslcertpath /etc/ssl/certs
If the server certificate has not been signed by a known CA (e.g. it is a self-signed certificate), then this certificate validation will always fail.
Certificate verification is always attempted. If it fails, by default a warning is printed but the connection carries on (which means you are not protected against attack). If your server's certificate has been properly set up and verifies correctly, then add the "sslcertck" option to enforce validation. If your server doesn't have a valid certificate though (e.g. it has a self-signed certificate) then it will never verify, and the only way you can protect yourself is by checking the fingerprint.
To check the peer fingerprint: first use fetchmail -v once to connect to the host, at a time when you are pretty sure that there is no attack in progress (e.g. you are not traversing any untrusted network to reach the server). Make a note of the fingerprint shown. Now embed this in your .fetchmailrc using the sslfingerprint option: e.g.
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslfingerprint "67:3E:02:94:D3:5B:C3:16:86:71:37:01:B1:3B:BC:E2"
When you next connect, the public key presented by the server will be verified against the fingerprint given. If it's different, it may mean that a man-in-the-middle attack is in progress - or it might just mean that the server changed its key. It's up to you to determine which has happened.
Some servers advertise STLS (POP3) or STARTTLS (IMAP), and fetchmail will automatically attempt TLS negotiation if SSL was enabled at compile time. This can however cause problems if the upstream didn't configure his certificates properly.
In order to prevent fetchmail from trying TLS (STLS, STARTTLS) negotiation, add this option:
sslproto ssl23
This restricts fetchmail's SSL/TLS protocol choice from the default "SSLv2, SSLv3, TLSv1" to the two SSL variants, disabling TLSv1. Note however that this causes the connection to be unencrypted unless an encrypting "plugin" is used or SSL is requested explicitly.
Fetchmail itself is probably working, but your SMTP port 25 listener is down or inaccessible.
The first thing to check is if you can telnet to port 25 on your smtp host (which is normally 'localhost' unless you've specified an smtp option in your .fetchmailrc or on the command line) and get a greeting line from the listener. If the SMTP host is inaccessible or the listener is down, fix that first.
In Red Hat Linux 6.x, SMTP is disabled by default. To fix this, set "DAEMON=yes" in your /etc/sys (STLShey are preauthenticated in this mode, so you'll actually have to ship your password. It will be under ssh encryption, though, so that shouldn't be a problem.
Fetchmail can use RFC1731 GSSAPI authorization to safely identify you to your IMAP server, as long as you can share Kerberos V credentials with your mail host and you have a GSSAPI-capable IMAP server.
fetchmail does not compile in support for GSS by default, since it requires libraries from a Kerberos V distribution, such as MIT Kerberos or Heimdal Kerberos.
If you have these, compiling in GSS support is simple: add a
--with-gssapi=[/path/to/krb5/root] option to
configure. For instance, I have all of my Kerberos V libraries
installed under /usr/krb5 so I run configure
--with-gssapi=/usr/krb5
Setting up Kerberos V authentication is beyond the scope of this FAQ (you may find Jim Rome's paper How to Kerberize your site helpful), but you'll at least need to add a credential for imap/[mailhost] to the keytab of the mail server (IMAP doesn't just use the host key). Then you'll need to have your credentials ready on your machine (cf. kinit).
After that things are very simple. Set your protocol to imap-gss in your .fetchmailrc, and omit the password, since imap-gss doesn't need one. You can specify a username if you want, but this is only useful if your mailbox belongs to a username different from your Kerberos principal.
Now you don't have to worry about your password appearing in cleartext in your .fetchmailrc, or across the network.
You'll need to have the OpenSSL libraries installed, and they should at least be version 0.9.7. Configure with --with-ssl. If you have the OpenSSL libraries installed in commonly-used default locations, this will suffice. If you have them installed in a non-default location, you'll need to specify the OpenSSL installation directory as an argument to --with-ssl after an equal sign.
Fetchmail binaries built this way support ssl,
sslkey, and sslcert options that control
SSL encryption, and will automatically use tls if the
server offers it. You will need to have an SSL-enabled mailserver to
use these options. See the manual page for details and some words
of care on the limited security provided.
If your open OpenSSL session dies with a message that complains "PRNG not seeded", update or improve your operating system. This means that the OpenSSL library on your machine has been unable to locate a source of random bits from which to seed its random-number generator; normally these come from the /dev/urandom, and this message probably means your OS doesn't have that device.
An interactive program could seed the random number generator from keystroke timings or some other form of user input. Because fetchmail is primarily designed to run forever as a background daemon, that option is not available in this case.
If you don't have the libraries installed, but do have the OpenSSL utility toolkit, something like this may work (but will not authenticate the server):
poll MYSERVER port 993 plugin "openssl s_client -connect %h:%p"
protocol imap username MYUSERNAME password MYPASSWORD
You should note that SSL is only secure against a "man-in-the-middle" attack if the client is able to verify that the peer's public key is the correct one, and has not been substituted by an attacker. fetchmail can do this in one of two ways: by verifying the SSL certificate, or by checking the fingerprint of the peer's public key.
There are three parts to SSL certificate verification: checking that the domain name in the certificate matches the hostname you asked to connect to; checking that the certificate expiry date has not passed; and checking that the certificate has been signed by a known Certificate Authority (CA). This last step takes some preparation, as you need to install the root certificates of all the CA's which you might come across.
The easiest way to do this is using the root CA keys supplied in the OpenSSL distribution, which means you need to download and unpack the source tarball from www.openssl.org. Once you have done that:
mkdir /etc/ssl/certscp *.pem /etc/ssl/certs/$dir="/etc/ssl"Now in .fetchmailrc, set option sslcertpath to point to this directory:
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslcertpath /etc/ssl/certs
If the server certificate has not been signed by a known CA (e.g. it is a self-signed certificate), then this certificate validation will always fail.
Certificate verification is always attempted. If it fails, by default a warning is printed but the connection carries on (which means you are not protected against attack). If your server's certificate has been properly set up and verifies correctly, then add the "sslcertck" option to enforce validation. If your server doesn't have a valid certificate though (e.g. it has a self-signed certificate) then it will never verify, and the only way you can protect yourself is by checking the fingerprint.
To check the peer fingerprint: first use fetchmail -v once to connect to the host, at a time when you are pretty sure that there is no attack in progress (e.g. you are not traversing any untrusted network to reach the server). Make a note of the fingerprint shown. Now embed this in your .fetchmailrc using the sslfingerprint option: e.g.
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslfingerprint "67:3E:02:94:D3:5B:C3:16:86:71:37:01:B1:3B:BC:E2"
When you next connect, the public key presented by the server will be verified against the fingerprint given. If it's different, it may mean that a man-in-the-middle attack is in progress - or it might just mean that the server changed its key. It's up to you to determine which has happened.
Some servers advertise STLS (POP3) or STARTTLS (IMAP), and fetchmail will automatically attempt TLS negotiation if SSL was enabled at compile time. This can however cause problems if the upstream didn't configure his certificates properly.
In order to prevent fetchmail from trying TLS (STLS, STARTTLS) negotiation, add this option:
sslproto ssl23
This restricts fetchmail's SSL/TLS protocol choice from the default "SSLv2, SSLv3, TLSv1" to the two SSL variants, disabling TLSv1. Note however that this causes the connection to be unencrypted unless an encrypting "plugin" is used or SSL is requested explicitly.
Fetchmail itself is probably working, but your SMTP port 25 listener is down or inaccessible.
The first thing to check is if you can telnet to port 25 on your smtp host (which is normally 'localhost' unless you've specified an smtp option in your .fetchmailrc or on the command line) and get a greeting line from the listener. If the SMTP host is inaccessible or the listener is down, fix that first.
In Red Hat Linux 6.x, SMTP is disabled by default. To fix this, set "DAEMON=yes" in your /etc/sys (STLShey are preauthenticated in this mode, so you'll actually have to ship your password. It will be under ssh encryption, though, so that shouldn't be a problem.
Fetchmail can use RFC1731 GSSAPI authorization to safely identify you to your IMAP server, as long as you can share Kerberos V credentials with your mail host and you have a GSSAPI-capable IMAP server.
fetchmail does not compile in support for GSS by default, since it requires libraries from a Kerberos V distribution, such as MIT Kerberos or Heimdal Kerberos.
If you have these, compiling in GSS support is simple: add a
--with-gssapi=[/path/to/krb5/root] option to
configure. For instance, I have all of my Kerberos V libraries
installed under /usr/krb5 so I run configure
--with-gssapi=/usr/krb5
Setting up Kerberos V authentication is beyond the scope of this FAQ (you may find Jim Rome's paper How to Kerberize your site helpful), but you'll at least need to add a credential for imap/[mailhost] to the keytab of the mail server (IMAP doesn't just use the host key). Then you'll need to have your credentials ready on your machine (cf. kinit).
After that things are very simple. Set your protocol to imap-gss in your .fetchmailrc, and omit the password, since imap-gss doesn't need one. You can specify a username if you want, but this is only useful if your mailbox belongs to a username different from your Kerberos principal.
Now you don't have to worry about your password appearing in cleartext in your .fetchmailrc, or across the network.
You'll need to have the OpenSSL libraries installed, and they should at least be version 0.9.7. Configure with --with-ssl. If you have the OpenSSL libraries installed in commonly-used default locations, this will suffice. If you have them installed in a non-default location, you'll need to specify the OpenSSL installation directory as an argument to --with-ssl after an equal sign.
Fetchmail binaries built this way support ssl,
sslkey, and sslcert options that control
SSL encryption, and will automatically use tls if the
server offers it. You will need to have an SSL-enabled mailserver to
use these options. See the manual page for details and some words
of care on the limited security provided.
If your open OpenSSL session dies with a message that complains "PRNG not seeded", update or improve your operating system. This means that the OpenSSL library on your machine has been unable to locate a source of random bits from which to seed its random-number generator; normally these come from the /dev/urandom, and this message probably means your OS doesn't have that device.
An interactive program could seed the random number generator from keystroke timings or some other form of user input. Because fetchmail is primarily designed to run forever as a background daemon, that option is not available in this case.
If you don't have the libraries installed, but do have the OpenSSL utility toolkit, something like this may work (but will not authenticate the server):
poll MYSERVER port 993 plugin "openssl s_client -connect %h:%p"
protocol imap username MYUSERNAME password MYPASSWORD
You should note that SSL is only secure against a "man-in-the-middle" attack if the client is able to verify that the peer's public key is the correct one, and has not been substituted by an attacker. fetchmail can do this in one of two ways: by verifying the SSL certificate, or by checking the fingerprint of the peer's public key.
There are three parts to SSL certificate verification: checking that the domain name in the certificate matches the hostname you asked to connect to; checking that the certificate expiry date has not passed; and checking that the certificate has been signed by a known Certificate Authority (CA). This last step takes some preparation, as you need to install the root certificates of all the CA's which you might come across.
The easiest way to do this is using the root CA keys supplied in the OpenSSL distribution, which means you need to download and unpack the source tarball from www.openssl.org. Once you have done that:
mkdir /etc/ssl/certscp *.pem /etc/ssl/certs/$dir="/etc/ssl"Now in .fetchmailrc, set option sslcertpath to point to this directory:
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslcertpath /etc/ssl/certs
If the server certificate has not been signed by a known CA (e.g. it is a self-signed certificate), then this certificate validation will always fail.
Certificate verification is always attempted. If it fails, by default a warning is printed but the connection carries on (which means you are not protected against attack). If your server's certificate has been properly set up and verifies correctly, then add the "sslcertck" option to enforce validation. If your server doesn't have a valid certificate though (e.g. it has a self-signed certificate) then it will never verify, and the only way you can protect yourself is by checking the fingerprint.
To check the peer fingerprint: first use fetchmail -v once to connect to the host, at a time when you are pretty sure that there is no attack in progress (e.g. you are not traversing any untrusted network to reach the server). Make a note of the fingerprint shown. Now embed this in your .fetchmailrc using the sslfingerprint option: e.g.
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslfingerprint "67:3E:02:94:D3:5B:C3:16:86:71:37:01:B1:3B:BC:E2"
When you next connect, the public key presented by the server will be verified against the fingerprint given. If it's different, it may mean that a man-in-the-middle attack is in progress - or it might just mean that the server changed its key. It's up to you to determine which has happened.
Some servers advertise STLS (POP3) or STARTTLS (IMAP), and fetchmail will automatically attempt TLS negotiation if SSL was enabled at compile time. This can however cause problems if the upstream didn't configure his certificates properly.
In order to prevent fetchmail from trying TLS (STLS, STARTTLS) negotiation, add this option:
sslproto ssl23
This restricts fetchmail's SSL/TLS protocol choice from the default "SSLv2, SSLv3, TLSv1" to the two SSL variants, disabling TLSv1. Note however that this causes the connection to be unencrypted unless an encrypting "plugin" is used or SSL is requested explicitly.
Fetchmail itself is probably working, but your SMTP port 25 listener is down or inaccessible.
The first thing to check is if you can telnet to port 25 on your smtp host (which is normally 'localhost' unless you've specified an smtp option in your .fetchmailrc or on the command line) and get a greeting line from the listener. If the SMTP host is inaccessible or the listener is down, fix that first.
In Red Hat Linux 6.x, SMTP is disabled by default. To fix this, set "DAEMON=yes" in your /etc/sys (STLShey are preauthenticated in this mode, so you'll actually have to ship your password. It will be under ssh encryption, though, so that shouldn't be a problem.
Fetchmail can use RFC1731 GSSAPI authorization to safely identify you to your IMAP server, as long as you can share Kerberos V credentials with your mail host and you have a GSSAPI-capable IMAP server.
fetchmail does not compile in support for GSS by default, since it requires libraries from a Kerberos V distribution, such as MIT Kerberos or Heimdal Kerberos.
If you have these, compiling in GSS support is simple: add a
--with-gssapi=[/path/to/krb5/root] option to
configure. For instance, I have all of my Kerberos V libraries
installed under /usr/krb5 so I run configure
--with-gssapi=/usr/krb5
Setting up Kerberos V authentication is beyond the scope of this FAQ (you may find Jim Rome's paper How to Kerberize your site helpful), but you'll at least need to add a credential for imap/[mailhost] to the keytab of the mail server (IMAP doesn't just use the host key). Then you'll need to have your credentials ready on your machine (cf. kinit).
After that things are very simple. Set your protocol to imap-gss in your .fetchmailrc, and omit the password, since imap-gss doesn't need one. You can specify a username if you want, but this is only useful if your mailbox belongs to a username different from your Kerberos principal.
Now you don't have to worry about your password appearing in cleartext in your .fetchmailrc, or across the network.
You'll need to have the OpenSSL libraries installed, and they should at least be version 0.9.7. Configure with --with-ssl. If you have the OpenSSL libraries installed in commonly-used default locations, this will suffice. If you have them installed in a non-default location, you'll need to specify the OpenSSL installation directory as an argument to --with-ssl after an equal sign.
Fetchmail binaries built this way support ssl,
sslkey, and sslcert options that control
SSL encryption, and will automatically use tls if the
server offers it. You will need to have an SSL-enabled mailserver to
use these options. See the manual page for details and some words
of care on the limited security provided.
If your open OpenSSL session dies with a message that complains "PRNG not seeded", update or improve your operating system. This means that the OpenSSL library on your machine has been unable to locate a source of random bits from which to seed its random-number generator; normally these come from the /dev/urandom, and this message probably means your OS doesn't have that device.
An interactive program could seed the random number generator from keystroke timings or some other form of user input. Because fetchmail is primarily designed to run forever as a background daemon, that option is not available in this case.
If you don't have the libraries installed, but do have the OpenSSL utility toolkit, something like this may work (but will not authenticate the server):
poll MYSERVER port 993 plugin "openssl s_client -connect %h:%p"
protocol imap username MYUSERNAME password MYPASSWORD
You should note that SSL is only secure against a "man-in-the-middle" attack if the client is able to verify that the peer's public key is the correct one, and has not been substituted by an attacker. fetchmail can do this in one of two ways: by verifying the SSL certificate, or by checking the fingerprint of the peer's public key.
There are three parts to SSL certificate verification: checking that the domain name in the certificate matches the hostname you asked to connect to; checking that the certificate expiry date has not passed; and checking that the certificate has been signed by a known Certificate Authority (CA). This last step takes some preparation, as you need to install the root certificates of all the CA's which you might come across.
The easiest way to do this is using the root CA keys supplied in the OpenSSL distribution, which means you need to download and unpack the source tarball from www.openssl.org. Once you have done that:
mkdir /etc/ssl/certscp *.pem /etc/ssl/certs/$dir="/etc/ssl"Now in .fetchmailrc, set option sslcertpath to point to this directory:
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslcertpath /etc/ssl/certs
If the server certificate has not been signed by a known CA (e.g. it is a self-signed certificate), then this certificate validation will always fail.
Certificate verification is always attempted. If it fails, by default a warning is printed but the connection carries on (which means you are not protected against attack). If your server's certificate has been properly set up and verifies correctly, then add the "sslcertck" option to enforce validation. If your server doesn't have a valid certificate though (e.g. it has a self-signed certificate) then it will never verify, and the only way you can protect yourself is by checking the fingerprint.
To check the peer fingerprint: first use fetchmail -v once to connect to the host, at a time when you are pretty sure that there is no attack in progress (e.g. you are not traversing any untrusted network to reach the server). Make a note of the fingerprint shown. Now embed this in your .fetchmailrc using the sslfingerprint option: e.g.
poll pop3.example.com proto pop3 uidl no dns user foobar@example.com password xyzzy is foobar ssl sslfingerprint "67:3E:02:94:D3:5B:C3:16:86:71:37:01:B1:3B:BC:E2"
When you next connect, the public key presented by the server will be verified against the fingerprint given. If it's different, it may mean that a man-in-the-middle attack is in progress - or it might just mean that the server changed its key. It's up to you to determine which has happened.
Some servers advertise STLS (POP3) or STARTTLS (IMAP), and fetchmail will automatically attempt TLS negotiation if SSL was enabled at compile time. This can however cause problems if the upstream didn't configure his certificates properly.
In order to prevent fetchmail from trying TLS (STLS, STARTTLS) negotiation, add this option:
sslproto