[Exim] MBX, UW imapd & vanishing messages

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Author: Mark Rigby-Jones
Date:  
To: exim-users
Subject: [Exim] MBX, UW imapd & vanishing messages
Good afternoon,

I'm running a system using Exim doing native delivery into MBX mailboxes
with UW IMAPd on the other side. Recently we spotted a message which
appeared to disappear completely - exim logs reported it successfully
delivered into the local mailbox, but it never appeared there.

I did some testing using the perl below to throw lots of messages at exim,
whilst using pine to thrash the mailbox through imapd (constant viewing
/flaging deleted/undeleted etc). A couple of test runs had 60-70 of the
10,000 messages vanshing completely, and around 20-30 deferred.

foreach $i (0..9999) {
    print "\r$i ";
    open(EXIM, "| ./exim -oMr local mrjtest");
    printf EXIM "Subject: %04.d\n\nTest Message\n.\n", $i;
    close(EXIM);
}


Poking around the exim & c-client revealed that Exim was locking using
fcntl(), whilst UW imapd was using flock(). On linux (certainly 2.2.x),
these are entirely independant, so I hacked exim to do mbx locking using
flock and retested. This time I got well over 100 deferred messages,
suiggesting the locking was working better, but still 16 emails vanished
completely.

Has anyone else seen (or can reproduce) this behaviour? Anyone have any
tips on how to get more reliable delivery into MBX mailboxes?

NB. I did try using UW imap's tmail to do the local deliveries, but aside
from being an order of magnitude slower, my test bugged out after around
140 messages with a bunch of errors like those below and 13 missing
messages.

2002-07-25 12:09:05 17XgUT-0005VC-00 Cannot open main log file
"/var/spool/exim/log/mainlog": Too many open files in system: euid=90 egid=90
2002-07-25 12:09:05 17XgUT-0005VC-00 Cannot open main log file
"/var/spool/exim/log/mainlog": Too many open files in system: euid=90 egid=90
exim: could not open panic log - aborting: original error above
2002-07-25 11:09:06 Exim configuration error in line 202: group exim was not
found

mrj
--
              Mark Rigby-Jones, Head of Systems, ts.com Ltd
      Windsor House, 12 High Street, Kidlington, Oxford OX5 2PJ, UK
   Tel: +44-1865-856000 (Direct: +44-1865-856009) Fax: +44-1865-856001
            mrj@??? <*> http://www.community.net.uk/~mrj/