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qmail/FAQ
D. J. Bernstein af9625ddf9 qmail 1.01
2009-12-18 13:07:04 +01:00

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1. Controlling the appearance of outgoing messages
1.1. How do I set up host masquerading?
1.2. How do I set up user masquerading?
2. Routing outgoing messages
2.1. How do I send local messages to another host?
2.2. How do I set up a null client?
2.3. How do I send outgoing mail through UUCP?
2.4. How do I set up a separate queue for a SLIP/PPP link?
2.5. How do I deal with ``CNAME lookup failed temporarily''?
3. Routing incoming messages by host
3.1. How do I receive mail for another host name?
3.2. How do I set up a virtual domain?
3.3. How do I set up several virtual domains for one user?
4. Routing incoming messages by user
4.1. How do I forward unrecognized usernames to another host?
4.2. How do I set up a mailing list?
4.3. How do I use majordomo with qmail?
4.4. How do I use procmail with qmail?
4.5. How do I use elm's filter with qmail?
4.6. How do I create aliases with dots?
5. Setting up servers
5.1. How do I run qmail-smtpd under tcpserver?
5.2. How do I set up qmail-qmtpd?
5.3. How do I set up qmail-pop3d?
5.4. How do I allow selected clients to use this host as a relay?
5.5. How do I fix up messages from broken SMTP clients?
6. Configuring MUAs to work with qmail
6.1. How do I make BSD mail generate a Date with the local time zone?
6.2. How do I stop pine from crashing?
6.3. How do I make MH work with qmail?
6.4. How do I stop Sun's dtcm from hanging?
7. Managing the mail system
7.1. How do I safely stop qmail-send?
7.2. How do I manually run the queue?
7.3. How do I rejuvenate a message?
7.4. How do I organize a big network?
7.5. How do I back up and restore the queue disk?
8. Miscellany
8.1. How do I tell qmail to do more deliveries at once?
8.2. How do I keep a copy of all incoming and outgoing mail messages?
8.3. How do I switch slowly from sendmail to qmail?
1. Controlling the appearance of outgoing messages
1.1. How do I set up host masquerading? All the users on this host,
zippy.af.mil, are users on af.mil. When joe sends a message to fred, the
message should say ``From: joe@af.mil'' and ``To: fred@af.mil'', without
``zippy'' anywhere.
Answer: echo af.mil > /var/qmail/control/defaulthost; chmod 644
/var/qmail/control/defaulthost.
1.2. How do I set up user masquerading? I'd like my own From lines to
show boss@af.mil rather than god@heaven.af.mil.
Answer: Add MAILHOST=af.mil and MAILUSER=boss to your environment. To
override From lines supplied by your MUA, add QMAILINJECT=f to your
environment.
2. Routing outgoing messages
2.1. How do I send local messages to another host? All the mail for
af.mil should be delivered to our disk server, pokey.af.mil. I've set up
an MX from af.mil to pokey.af.mil, but when a user on the af.mil host
sends a message to boss@af.mil, af.mil tries to deliver it locally. How
do I stop that?
Answer: Remove af.mil from /var/qmail/control/locals. If qmail-send is
running, give it a HUP. Make sure the MX is set up properly before you
do this. Also make sure that pokey can receive mail for af.mil---see
question 3.1.
2.2. How do I set up a null client? I'd like zippy.af.mil to
send all mail to bigbang.af.mil.
Answer: echo :bigbang.af.mil > /var/qmail/control/smtproutes;
chmod 644 /var/qmail/control/smtproutes. Disable local delivery as in
question 2.1. Turn off qmail-smtpd in /etc/inetd.conf.
2.3. How do I send outgoing mail through UUCP? I need qmail to send all
outgoing mail via UUCP to my upstream UUCP site, gonzo.
Answer: Put
:alias-uucp
into control/virtualdomains and
|preline -df /usr/bin/uux - -r -gC -a"$SENDER" gonzo!rmail "($EXT2@$HOST)"
into ~alias/.qmail-uucp-default. (For some UUCP software you will need
to use -d instead of -df. Also, you may need to insert a space between
-a and "$SENDER" for bounces to work properly.) If qmail-send is
running, give it a HUP.
2.4. How do I set up a separate queue for a SLIP/PPP link?
Answer: Use serialmail (http://pobox.com/~djb/serialmail.html).
2.5. How do I deal with ``CNAME lookup failed temporarily''? The log
showed that a message was deferred for this reason. Why is qmail doing
CNAME lookups, anyway?
Answer: The SMTP standard does not permit aliased hostnames, so qmail
has to do a CNAME lookup in DNS for every sender and recipient host. If
the relevant DNS server is down, qmail defers the message. It will try
again soon.
3. Routing incoming messages by host
3.1. How do I receive mail for another host name? I'd like our disk
server, pokey.af.mil, to receive mail addressed to af.mil. I've set up
an MX from af.mil to pokey.af.mil, but how do I get pokey to treat
af.mil as a name for the local host?
Answer: Add af.mil to /var/qmail/control/locals and to
/var/qmail/control/rcpthosts. If qmail-send is running, give it a HUP.
3.2. How do I set up a virtual domain? I'd like any mail for
nowhere.mil, including root@nowhere.mil and postmaster@nowhere.mil and
so on, to be delivered to Bob. I've set up the MX already.
Answer: Put
nowhere.mil:bob
into control/virtualdomains. Add nowhere.mil to control/rcpthosts. If
qmail-send is running, give it a HUP.
Now mail for whatever@nowhere.mil will be delivered locally to
bob-whatever. Bob can set up ~bob/.qmail-default to catch all the
possible addresses, ~bob/.qmail-info to catch info@nowhere.mil, etc.
3.3. How do I set up several virtual domains for one user? Bob wants
another virtual domain, everywhere.org, but he wants to handle
nowhere.mil users and everywhere.org users differently. How can we do
that without setting up a second account?
Answer: Put two lines into control/virtualdomains:
nowhere.mil:bob-nowhere
everywhere.org:bob-everywhere
Add nowhere.mil and everywhere.org to control/rcpthosts. If qmail-send
is running, give it a HUP.
Now Bob can set up separate .qmail-nowhere-* and everywhere-* files. He
can even set up .qmail-nowhere-default and .qmail-everywhere-default.
4. Routing incoming messages by user
4.1. How do I forward unrecognized usernames to another host? I'd like
to set up a LUSER_RELAY pointing at bigbang.af.mil.
Answer: Put
| forward "$LOCAL"@bigbang.af.mil
into ~alias/.qmail-default.
4.2. How do I set up a mailing list? I'd like me-sos@my.host.name to be
forwarded to a bunch of people.
Answer: Put a list of addresses into ~me/.qmail-sos, one per line. Then
incoming mail for me-sos will be forwarded to each of those addresses.
You should also touch ~me/.qmail-sos-owner so that bounces come back to
you rather than the original sender. If you want subscriptions to be
handled automatically, put
| qlist2 sos my.host.name
into ~me/.qmail-sos-request. Anyone who wants to subscribe can simply
send a message to me-sos-request@my.host.name.
4.3. How do I use majordomo with qmail?
Answer: You need to patch majordomo so that it creates qmail-style
lists. See ftp://koobera.math.uic.edu/pub/software/majordomo+qmail.gz.
Exception: qmsmac understands sendmail-style :include: files, so you
shouldn't patch majordomo if you're using qmsmac.
4.4. How do I use procmail with qmail?
Answer: Put
| preline procmail
into ~/.qmail. You'll have to use a full path for procmail unless
procmail is in the system's startup PATH. Note that procmail will try to
deliver to /usr/spool/mail/$USER by default; to change this, change
SYSTEM_MBOX in procmail's config.h.
4.5. How do I use elm's filter with qmail?
Answer: Put
| preline filter
into ~/.qmail. You'll have to use a full path for filter unless filter
is in the system's startup PATH.
4.6. How do I create aliases with dots? I tried setting up
~alias/.qmail-P.D.Q.Bach, but it doesn't do anything.
Answer: Use .qmail-p:d:q:bach. Dots are converted to colons, and
uppercase is converted to lowercase.
5. Setting up servers
5.1. How do I run qmail-smtpd under tcpserver? inetd is barfing at high
loads, cutting off service for ten-minute stretches. I'd also like
better connection logging.
Answer: First, install the tcpserver program, part of the ucspi-tcp
package (http://pobox.com/~djb/ucspi-tcp.html). Second, remove the smtp
line from /etc/inetd.conf, and put the line
tcpserver -u 7770 -g 2108 0 smtp /var/qmail/bin/qmail-smtpd &
into your system startup files. Replace 7770 with your qmaild uid, and
replace 2108 with your nofiles gid. Don't forget the &. The change will
take effect at your next reboot.
By default, tcpserver allows at most 40 simultaneous qmail-smtpd
processes. To raise this limit to 400, use tcpserver -c 400. To keep
track of who's connecting and for how long, run (on two lines)
tcpserver -v -u 7770 -g 2108 0 smtp /var/qmail/bin/qmail-smtpd \
2>&1 | /var/qmail/bin/splogger smtpd 3 &
5.2. How do I set up qmail-qmtpd?
Answer: Two steps. First, put a
qmtp 209/tcp
line into /etc/services. Second, put (all on one line)
qmtp stream tcp nowait qmaild
/var/qmail/bin/tcp-env tcp-env /var/qmail/bin/qmail-qmtpd
into /etc/inetd.conf, and give inetd a HUP.
If you have tcpserver installed, skip the inetd step, and set up
tcpserver -u 7770 -g 2108 0 qmtp /var/qmail/bin/qmail-qmtpd &
replacing 7770 and 2108 with the qmaild uid and nofiles gid. See
question 5.1 for more details.
5.3. How do I set up qmail-pop3d?
Answer: Four steps. First, install the checkpassword program
(http://pobox.com/~djb/checkpwd.html). Second, make sure you have a
pop3 110/tcp
line in /etc/services. Third, put (all on one line)
pop3 stream tcp nowait root /var/qmail/bin/qmail-popup
qmail-popup YOURHOST /bin/checkpassword /var/qmail/bin/qmail-pop3d Maildir
into /etc/inetd.conf, and give inetd a HUP; replace YOURHOST with your
host's fully qualified domain name. Fourth, set up Maildir delivery for
any user who wants to read mail via POP.
If you have tcpserver installed, skip the inetd step, and set up (on two
lines)
tcpserver 0 pop3 /var/qmail/bin/qmail-popup YOURHOST \
/bin/checkpassword /var/qmail/bin/qmail-pop3d Maildir &
replacing YOURHOST with your host's fully qualified domain name. See
question 5.1 for more details.
Security note: pop3d should be used only within a secure network;
otherwise an eavesdropper can steal passwords.
5.4. How do I allow selected clients to use this host as a relay? I see
that qmail-smtpd rejects messages to any host not listed in
control/rcpthosts. I know I could entirely disable this feature by
removing control/rcpthosts, but I want to be more selective.
Answer: Three steps. First, install tcp-wrappers, available separately,
including hosts_options. Second, change your qmail-smtpd line in
inetd.conf to
smtp stream tcp nowait qmaild /usr/local/bin/tcpd
/var/qmail/bin/tcp-env /var/qmail/bin/qmail-smtpd
(all on one line) and give inetd a HUP. Third, in tcpd's hosts.allow,
make a line setting the environment variable RELAYCLIENT to the empty
string for the selected clients:
tcp-env: 1.2.3.4, 1.2.3.5: setenv = RELAYCLIENT
Here 1.2.3.4 and 1.2.3.5 are the clients' IP addresses. qmail-smtpd
ignores control/rcpthosts when RELAYCLIENT is set. (It also appends
RELAYCLIENT to each envelope recipient address. See question 5.5 for an
application.)
Alternative procedure, if you are using tcpserver: Install tcpcontrol
(http://pobox.com/~djb/tcpcontrol.html). Create /etc/tcp.smtp containing
1.2.3.6:allow,RELAYCLIENT=""
127.:allow,RELAYCLIENT=""
to allow clients with IP addresses 1.2.3.6 and 127.*. Run
tcpmakectl /etc/tcp.smtp.cdb /etc/tcp.smtp.tmp < /etc/tcp.smtp
Finally, insert
tcpcontrol /etc/tcp.smtp.cdb
before /var/qmail/bin/qmail-smtpd in your tcpserver line.
5.5. How do I fix up messages from broken SMTP clients?
Answer: Three steps. First, put
| [ "@$HOST" = "@fixme" ] || ( echo Permission denied; exit 100 )
| qmail-inject -f "$SENDER" -- "$EXT2"
into ~alias/.qmail-fixup-default. Second, put
fixme:fixup
into /var/qmail/control/virtualdomains, and give qmail-send a HUP.
Third, follow the procedure in question 5.4, but set RELAYCLIENT to the
string ``@fixme'':
tcp-env: 1.2.3.6, 1.2.3.7: setenv = RELAYCLIENT @fixme
Here 1.2.3.6 and 1.2.3.7 are the clients' IP addresses. If you are using
tcpserver and tcpcontrol instead of inetd and tcpd, put
1.2.3.6:allow,RELAYCLIENT="@fixme"
1.2.3.7:allow,RELAYCLIENT="@fixme"
into /etc/tcp.smtp, and run tcpmakectl as in question 5.4.
6. Configuring MUAs to work with qmail
6.1. How do I make BSD mail generate a Date with the local time zone?
When I send mail, I'd rather use the local time zone than GMT, since
some MUAs don't know how to display Date in the receiver's time zone.
Answer: Put
set sendmail=/var/qmail/bin/datemail
into your .mailrc or your system-wide Mail.rc. Beware that BSD mail is
neither secure nor reliable.
6.2. How do I stop pine from crashing? When I ask any version of pine
past 3.91 to send mail, it crashes.
Answer: Put
sendmail-path=/usr/lib/sendmail -oem -oi -t
into /usr/local/lib/pine.conf. (This will work with sendmail too.)
Beware that pine is neither secure nor reliable.
6.3. How do I make MH work with qmail?
Answer: Put
postproc: /usr/mh/lib/spost
into each user's .mh_profile. (This will work with sendmail too.) Beware
that MH is neither secure nor reliable.
6.4. How do I stop Sun's dtcm from hanging?
Answer: There is a novice programming error in dtcm, known as ``failure
to close the output side of the pipe in the child.'' Sun has, at the
time of this writing, not yet provided a patch. Sorry.
7. Managing the mail system
7.1. How do I safely stop qmail-send? Back when we were running
sendmail, it was always tricky to kill sendmail without risking the loss
of current deliveries; what should I do with qmail-send?
Answer: Go ahead and kill the qmail-send process. It will shut down
cleanly. Wait for ``exiting'' to show up in the log. To restart it, run
qmail-start the same way as it's run from your system boot scripts.
7.2. How do I manually run the queue? I'd like qmail to try delivering
all the remote messages right now.
Answer: Give the qmail-send process an ALRM.
7.3. How do I rejuvenate a message? Somebody broke into Eric's computer
again; it's going to be down for at least another two days. I know Eric
has been expecting an important message---in fact, I see it sitting here
in /var/qmail/queue/mess/15/26902. It's been in the queue for six days;
how can I make sure it isn't bounced tomorrow?
Answer: Just touch /var/qmail/queue/info/15/26902. (This is the only
form of queue modification that's safe while qmail is running.)
7.4. How do I organize a big network? I have a lot of machines, and I
don't know where to start.
Answer: First, choose the domain name where your users will receive
mail. This is normally the shortest domain name you control. If you are
in charge of *.movie.edu, you can use addresses like joe@movie.edu.
Second, choose the machine that will know what to do with different
users at movie.edu. Set up a host name in DNS for this machine:
mailhost.movie.edu IN A 1.2.3.4
4.3.2.1.in-addr.arpa IN PTR mailhost.movie.edu
Here 1.2.3.4 is the IP address of that machine.
Third, make a list of machines where mail should end up. For example, if
mail for Bob should end up on Bob's workstation, put Bob's workstation
onto the list. For each of these machines, set up a host name in DNS:
bobshost.movie.edu IN A 1.2.3.7
7.3.2.1.in-addr.arpa IN PTR bobshost.movie.edu
Fourth, install qmail on bobshost.movie.edu. qmail will automatically
configure itself to accept messages for bob@bobshost.movie.edu and
deliver them to ~bob/Mailbox on bobshost. Do the same for the other
machines where mail should end up.
Fifth, install qmail on mailhost.movie.edu. Put
movie.edu:alias-movie
into control/virtualdomains on mailhost. Then forward bob@movie.edu to
bob@bobshost.movie.edu, by putting
bob@bobshost.movie.edu
into ~alias/.qmail-movie-bob. Do the same for other users.
Sixth, put movie.edu into control/rcpthosts on mailhost.movie.edu, so
that mailhost.movie.edu will accept messages for users at movie.edu.
Seventh, set up an MX record in DNS to deliver movie.edu messages to
mailhost:
movie.edu IN MX 10 mailhost.movie.edu
Eighth, on all your machines, put movie.edu into control/defaulthost.
7.5. How do I back up and restore the queue disk?
Answer: You can't.
One difficulty is that you can't get a consistent snapshot of the queue
while qmail-send is running. Another difficulty is that messages in the
queue must have filenames that match their inode numbers.
However, the big problem is that backups---even twice-daily backups---
are far too unreliable for mail. If your disk dies, there will be very
little overlap between the messages saved in the last backup and the
messages that were lost.
There are several ways to add real reliability to a mail server. Battery
backups will keep your server alive, letting you park the disk to avoid
a head crash, when the power goes out. Solid-state disks have their own
battery backups. RAID boxes let you replace dead disks without losing
any data.
8. Miscellany
8.1. How do I tell qmail to do more deliveries at once? It's running
only 20 parallel qmail-remote processes.
Answer: Decide how many deliveries you want to allow at once. Put that
number into control/concurrencyremote. Restart qmail-send as in question
7.1. If your system has resource limits, make sure you set the
descriptors limit to at least double the concurrency plus 5; otherwise
you'll get lots of unnecessary deferrals whenever a big burst of mail
shows up. Note that qmail also imposes a compile-time concurrency limit,
120 by default; this is set in conf-spawn.
8.2. How do I keep a copy of all incoming and outgoing mail messages?
Answer: Set QUEUE_EXTRA to "Tlog\0" and QUEUE_EXTRALEN to 5 in extra.h.
Recompile qmail. Put ./msg-log into ~alias/.qmail-log.
You can also use QUEUE_EXTRA to, e.g., record the Message-ID of every
message: run
| awk '/^$/ { exit } /^[mM][eE][sS][sS][aA][gG][eE]-/ { print }'
from ~alias/.qmail-log.
8.3. How do I switch slowly from sendmail to qmail? I'm thinking of
moving the heaven.af.mil network over to qmail, but first I'd like to
give my users a chance to try out qmail without affecting current
sendmail deliveries. We're using NFS.
Answer: Find a host in your network, say pc.heaven.af.mil, that isn't
running an SMTP server. (If addresses at pc.heaven.af.mil are used, you
should already have an MX pointing pc.heaven.af.mil to your mail hub.)
Set up a new MX record pointing lists.heaven.af.mil to pc.heaven.af.mil.
Install qmail on pc.heaven.af.mil. Replace pc with lists in the control
files. Make the qmail man pages available on all your machines.
Now tell your users about qmail. A user can forward joe@heaven.af.mil to
joe@lists.heaven.af.mil to get ~/Mailbox delivery; he can set up .qmail
files; he can start running his own mailing lists @lists.heaven.af.mil.
When you're ready to turn sendmail off, you can set up pc.heaven.af.mil
as your new mail hub. Add heaven.af.mil to control/locals, and change
the heaven.af.mil MX to point to pc.heaven.af.mil. Make sure you leave
lists.heaven.af.mil in control/locals so that transition addresses will
continue to work.
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