+++ /dev/null
-From mlievaart@orion.nl Mon Jan 10 10:46:33 2000
-From: Martijn Lievaart <mlievaart@orion.nl>
-To: Eric S. Raymond <esr@thyrsus.com>
-Date: zondag 9 januari 2000 0:38
-Subject: Re: Thanks for fetchmail and a solution to the multidrop problem (I
-Status: O
-Content-Length: 8086
-Lines: 226
-
-think)
-
-Hello Eric,
-
-Let me first state that I'm no sendmail nor unix guru, so although this
-seems to work, I certainly would not say this is the "best" solution. In
-fact I would welcome all comments to make this better. In particular, it
-seems that that the mailertable feature was made just for this, but I'm
-still studying that.
-
-Also, This mail will have lines wrapped. I will put up this on a website
-asap, so people can download the relevant portions. In the meantime, I'm
-using (stuck on) Outlook, so I won't even attempt to format this mail.
-Accept my apoligies and try to mentally reconnect the lines.
-
-Finally, this mail is a bit lengthy, but I guess it is better to get all
-information in, so please bear with me.
-
-After some very frustrating attempts to get multidrop to work reliably, it
-suddenly hit me. When sendmail has translated the recipient to the mailbox,
-the recipient is gone (in the cases we're talking about). So the solution is
-not to let sendmail do this translation (completely).
-
-The trick is to let a custom MDA be called with both the mailbox and the
-full recipient name. This MDA then just stuffs it in the correct mailbox
-after adding the appropriate headers. Luckily I hit on the formail utility.
-It reformats a mailmessage and does just what I wanted. Specifically my
-script uses it to:
-- add a custom header (default: "Delivered-To:") with the recipient
-- rewrite the message-ID, so fetchmail will download the same message
-multiple times.
-- add another header, just for fun.
-
-The rewriting of the message-ID is needed because fetchmail will suppress
-multiple messages with the same ID, normally a good idea, but now it gets in
-the way. A switch on fetchmail to suppress this behaviour would be great.
-
-At first I hardcoded the domains in the sendmail.cf, but I quickly set out
-to do one better and came up with the following solution. In sendmail.cf,
-add the following line somewhere at the top.
-
-Kmultidroptable hash -o /etc/mail/multidroptable
-
-this defines a table for all domains we want to use multidrop for. The
-format of this file is multiple lines of the format:
-<domain> <mailbox>
-
-e.g:
-mailtest.orion.nl mailtest
-mailtest2.orion.nl mailtest
-mailtest3.orion.nl mailtest
-bvh-communicatie.nl b.bvh
-krakatau.nl b.bvh
-personeelzaak.nl b.bvh
-maslowassociates.nl b.bvh
-rtij.nl rtij
-
-Of course, create a .db file with makemap. Also, the domains must be added
-to class w, so they should be added to your sendmail.cw or RelayTo file, or
-whatever you use.
-
-Now add to sendmail.cf:
-
-R$+ < @ $* . > $: <MULTIDROP> $(multidroptable $2
-$: <NO> $) <?> $1 < @ $2 . >
-R<MULTIDROP> <NO> <?> $* $: $1
-R<MULTIDROP> $+ <?> $+ < @ $* . > $#drop $@ $2 @ $3 $: $1
-
-These lines should be above the existing lines that read:
-
-# short circuit local delivery so forwarded email works
-R$=L < @ $=w . > $#local $: @ $1 special local names
-R$+ < @ $=w . > $#local $: $1 regular local name
-
-This works as follows (in fact these comments are above my modification in
-our sendmail.cf).
-#
-# MLI. Any drop host gets passed to the drop script
-#
-# The first rule looks up the domain in the multidrop table.
-# The input at this point is always:
-# user@<dom.ain.>
-# If found, the resulting line looks like this:
-# <MULTIDROP> mailbox <?> user@<dom.ain.>
-# if not found, the resulting line will be:
-# <MULTIDROP> <NO> <?> user@<dom.ain.>
-# The second line restores the "not found" case back to user@<dom.ain.>
-# So if this domain was found in the multidroptable, we still have a line
-starting with <MULTIDROP>
-# as shown above. The third line hands this to the drop script.
-#
-# Note that the user ($:) is the mailbox this message should be stuffed in,
-the host ($@) is the full
-# user@<dom.ain>. This is how the dropscript expects it.
-#
-
-I guess sendmail guru's are now laughing their pants off, and I hope someone
-will show me a better way to achieve this. For now, it works.
-
-Next, we need to define mailer drop (somewhere in the sendmail.cf)
-
-#
-# multidrop pop3 support.
-#
-
-Mdrop, P=/usr/local/bin/dropmail, F=lFS,
- T=X-Unix,
- A=dropmail $u $h
-
-The S flag here is crucial, otherwise the dropmail script won't run as root,
-and under linux (==bash) suid scripts are not permited. I gather most unices
-now disalow suid scripts, so this would be necessary on most unices. There
-probably are other flags that would make this better, but this works, so I
-decided to divert my attention to other tasks at hand (busy, busy, busy....
-;^>).
-
-Now we only need the dropmail script, /usr/local/bin/dropmail, mode 700. It
-looks big, but effectively one pipeline does the real work. The rest is
-configuration, error checking and locking the mailbox.
-
-#!/bin/bash
-
-#
-# Script to force a mail message in a format that fetchmail will recognise.
-# use as a MDA from sendmail. Must be executed with F=S.
-#
-
-#
-# Configuration:
-#
-maildir=/var/spool/mail
-envelope=Delivered-To:
-
-#
-# set PATH to a known value to avoid some security issues
-#
-export PATH=/bin:/usr/bin
-
-#
-#
-#
-to=$2
-user=$1
-mbox=$maildir/$user
-
-#
-# If the mailbox does not exist, create it. Note that we act pretty
-paranoid, this is hopefully
-# resistant to symlink attacks
-#
-if [ ! -f $mbox ]
-then
- oldumask=`umask`
- umask 077
- touch $mbox
- chmod 660 $mbox || exit 1
- chown $user $mbox || exit 1
- chgrp mail $mbox || exit 1
- umask $oldumask
-fi
-
-# First lock the mailbox, if this doesn't succeed in 64 seconds, give up and
-send
-# mail to postmaster.
-# If this period is to short, increase the retries (-r flag to lockfile)
-#
-# Then run the message through formail to get it into the right mailbox
-format with the
-# right headers added.
-#
-# Delivered-To will make fetchmail propagate this mail to the correct user
-when
-# run with '-E "Delivered-To"'. Set this in the advanced settings of the
-TeamInternet f.i.
-# (if you changed the envelope at the start of this script, adapt this
-accordingly)
-#
-# We also muck up the messageid, so fetchmail will never skip a message on
-the basis of
-# duplicate messageIDs. The -i "Message-ID" will rename the old message ID,
-the -a will
-# add a new one.
-#
-# Lastly, we add a header indicating which host did the rewriting.
-#
-
-if lockfile -r 8 $mbox.lock >/dev/null 2>&1
-then
- cat - | formail -i "$envelope <$to>" -i "Message-ID:" -a
-"Message-ID:" -i "X-Multidrop-Processing: <`hostname`>" >>$mbox
- rm -f $mbox.lock
-else
- (echo "Subject: Cannot lock mailbox for $user" & cat -) |
-/usr/lib/sendmail postmaster
-fi
-
-#
-# EOF
-#
-
-This obviously is very Linux (even RedHat?) dependant, locking mailboxes,
-creating mailboxes with the right permissions, probably even bash dependent.
-I would say that it should be fairly easy to port to other systems, but
-alas, my unix knowledge is lacking for that. I'll also rewrite it someday,
-a.o. that umask handling can be done much better and the location of the
-sendmail binairy should not be fixed.
-
-Now the only thing left to do is to retrieve the mail with fetchmail, using
-'envelope "Delivered-To:"' in the poll line. The above script has added this
-line, so this is all that fetchmail needs.
-
-All parts of this solution need carefull examination. In particular I think
-the new rule lines may not catch all cases, although they worked for
-everything I threw at them and work satisfactorily in production. I'm also
-wondering if there is a more standard way to drop something in a mailbox. I
-yet have to investigate procmail, but all other MDA's mucked with the
-message and effectively undid my carefully added header. I'll experiment
-some more and rethink it all as I learn more.
-
-I'm still wondering, if I can get formail to include another received
-line.... "Received from localhost by dropmail for <user>...." to make it
-work without the envelope flag. Well I'll have to experiment. Do you know if
-there is a header I can add so fetchmail works out-of-the-box?
-
-Regards,
-Martijn Lievaart
-
projects / ~andy / fetchmail / commitdiff