Out of Topic: IMAP

Bob Jones bob.jones at usg.edu
Thu Feb 8 18:20:55 CET 2007


Thus spake Scott Silva, with impeccable timing on 2/8/2007 11:37 AM:
> Richard Frovarp spake the following on 2/8/2007 8:19 AM:
>> Bob Jones wrote:
>>> Thus spake Richard Frovarp, with impeccable timing on 2/8/2007 10:26 AM:
>>>> We run IMAP and use mbx format. There are occasional issues when the
>>>> index is corrupted, but there are tools to fix it. Using mbx over
>>>> maildir prevents the system from having to read n files for the
>>>> required information, where n is the number of messages in the
>>>> folder. As you might expect n can grow to be quite large.
>>> While this may be true in UW-IMAP (not sure, never tried maildir with
>>> it), if you use something like dovecot that has an index cache of each
>>> mailbox, the system only has to read all those individual files once
>>> to create the cache.  In fact, if you use the LDA that comes with
>>> dovecot, when the message is delivered it is added to the index
>>> automatically, so the filesystem never has to worry about reading all
>>> those individual files, just each one as the client accesses to
>>> actually read the mail.
>>>
>>> Also, even if you are using mbox format, I highly recommend dovecot as
>>> it blows the doors off of UW even with that format.
>>>
>>> Bob
>>>
>> Quota handling seems to be a little odd in it. It says it doesn't play
>> well with file system quotas. The Maildir++ quota seems to be a bit more
>> difficult to work with than file system quotas. On first look, I don't
>> see any easy way to tell if a user is over quota or support for grace
>> periods.
> That is one negative. If a user goes over quota, they will get locked out with
> a cryptic and very terse message. The first time it happened to me, it took me
> hours to figure out what happened. Especially when the message from the quota
> daemon tries to go to an already over-quota user.

We don't have mail quotas here, so I've never had to worry about that, 
but I can see that as a negative.

> Another thing I miss about UW-imap is its logging of box accesses and
> activity. You got a nice message on when a user got their mail, and even if
> they left it or cleared it. I can't find any equivalent in dovecot. It is
> handy when a user says they didn't get something, and you can see that they
> did, but either deleted it or have a bad rule in their MUA.

Timo recently added (maybe via a plugin) an imap logging option that 
logs ever imap command a client issues.  I don't remember it exactly, 
but it was within the past few weeks.

Bob



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