Re: [exim] failed to lock mailbox

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Autor: Mike Grice
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Dla: John Hixson
CC: exim-users
Temat: Re: [exim] failed to lock mailbox
On Mon, 2005-05-16 at 13:25 -0700, John Hixson wrote:
> Yes, we are using mbox format. We allow both pop3 and imap connections
> as well. We host almost 1000 domains on the same box. Most mailboxes are
> set to 3-5mb quotas, while others are 20mb. The exim queue has nearly
> 20,000 messages sitting in it (spam , email to users who dont have a
> mailbox setup, etc), could this be related?


Hi,

For an MDA to deliver to a mbox-formatted mailbox, it has to gain an
exclusive lock before delivery starts (to guarantee the integrity of the
delivered message). If you have multiple accesses (as explained above)
then they will fight for exclusive access to the file. This is more a
failing of the mbox format than anything else. The large number of
messages in your queue could be an artifact of the high activity of the
machine, coupled with the fact that the delivery process can't get a
lock and will then have to defer.

I would suggest moving to a Maildir-style mailbox system (if you can!),
this would eliminate locking issues (and can be used over NFS safely if
you need to scale your platform later). I'm not sure how you solve this
problem any other way - however you could alleviate it by enforcing a
minimum time between checking messages for the users of the POP3/IMAP
service (but again, this is only a short-term workaround, not a full
fix).

Cheers,
Mike

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