IMAP server alternatives

[Ron Wilhoite]

On 7/11/2006 11:18 AM, Greg Groth wrote:
> On 7/11/2006 9:29 AM, albi wrote:
>> Erik Norgaard wrote:
>>
> 
> I would like to ask a couple more in depth questions pertaining to this 
> conversation.  We recently switched from POP3 & Outlook Express to IMAP 
> using IMAP-UW & Thunderbird.  Personally I have had no issues with 
> IMAP-UW, but the users in our office have had issues with the mbox 
> format itself.  Specifically they cannot store messages & subfolders 
> within a folder (referring to the Thunderbird definition of a folder). 
> In mbox, since a given folder is not a directory, but a file, you cannot 
> place a subfolder within that file.  Outlook Express' POP3 
> implementation did not have this behavior.  Right or wrong, my users 
> have requested that I attempt to restore this functionality in IMAP.  Am 
> I correct in assuming that if I switch to a mdir format server, it will 
> operate in the manner they are requesting?

I do this with Thunderbird and Dovecot using maildir for IMAP users.

> 
> My next question is in regards to scalability, not so much in the way of 
> users, but in the amount of mail they store.  Currently we have about 20 
> email accounts, and for the most part the users keep their email to a 
> reasonable amount.  However I do have 5 users that insist they save 
> everything, and do not clean out their InBoxes.  Currently they retain 
> email going back 5 years, and have mail folders in excess of a couple of 
> gigs apiece.  Since one of these people is the owner, I have little 
> chance of changing this policy.  However they are asking that I attempt 
> to increase the response time of the IMAP server, which can be somewhat 
> slow for them - especially through SquirrelMail.  Would the mdir format 
> help in this situation as well?

I saw a dramatic improvement in speed with both Thunderbird and 
Squirrelmail after switching from mbox to maildir.

> 
> Last question, how difficult is it to back up the mdir format? 
> Currently I cron a tar job, nightly, to backup the mboxes to another 
> server to allow for tape backups (the tape unit on the server in 
> question doesn't want to play nice with FreeBSD), and have had no 
> difficulty in accomplishing this.  Can I accomplish the same style of 
> backups when moving to mdir?

I rsync both mbox and maildir message stores with no problem. Tar should 
copy your maildir folders with no problem. You might be slightly 
surprised when you realize each message is a separate file with maildir.

> 
> I'm in the middle of setting up a server to try out various IMAP servers 
> to test which would provide the best response for our specific needs 
> (low number of users - high volume of saved email), and would appreciate 
> any opinions on the matter as it would probably save considerable time 
> picking the right software to begin with.
> 

Dovecot was simple to install (from ports), has sensible defaults, lets 
me seamlessly support POP and IMAP users (about 100), with inboxes 
(/var/mail/username) still in mbox format, but all other folders in 
maildir format for IMAP users.

Dovecot's developer, Timo Sirainen, is active and extremely helpful on 
the mailing list.

Ron Wilhoite