[Imap-uw] Large Mailboxes, POP and Server Load

[Erik Kangas]

Michael Cashwell wrote:
> On Sep 12, 2007, at 8:00 AM, Erik Kangas wrote:
>
>> We have noticed a trend that probably affects other users of UW 
>> IMAP.  In particular:
>>
>> * User with a large inbox (say 10,000 to 50,000 or more messages)
>> * Mailbox not checked in some time resulting in the large number of 
>> messages
>> * User decides to download and delete the email from the mailbox 
>> using POP
>>
>> ... However, we find that invariably when users are in this 
>> situation, the POP process eats up significant CPU continuously and 
>> drives up the load on the servers very significantly....
>>
>> Environment:
>> * RedHat Enterprise Linux v3 or 4
>> * UW IMAP 2006h
>> * MIX-formatted folders
>
> On that last point, are you sure the INBOX the mail is being delivered 
> to is MIX format? I think you have to take special steps with tmail to 
> get direct delivery into that format. Without this, I think, the 
> delivery mailbox will remain the aged mbox out in /var/mail/spool and 
> when the first IMAP or POP connection to the logical INBOX occurs the 
> server processes "slurps" those messages into the IMAP MIX inbox store.
>
> It sounds like this slurping is bogging things down. Someone else may 
> jump in with further info but until then check the archives for how to 
> get tmail to deliver directly to MIX.
It is definitely MIX and there is no slurping going in.  We use 
procmail+dmail to deliver to all folders and we do not use /var/mail/... 
for anything (except ORGMAIL in the case of some procmail failure).

Best,
-Erik Kangas