[Dovecot] Some POP3 questions

[Kenneth Kalmer]

Hi everyone

Been spending the whole day on the wiki and in the list archives on using
dovecot for POP3 mail. I'd like to present my findings and ask for some
feedback.

Our current software setup:

* Courier-IMAP running POP3/IMAP
* Postfix MTA
* MySQL backend for user and login info

As for the system layout, it looks like this:

* NFS server which is the same server that houses single Courier-IMAP
installation (Gentoo, 3GB memory)
* 2x Postfix instances delivering to NFS
* Mail directory structure: /mail/e/ex/example.com/user

Usage:

* Currently reaching in excess of 1,200 concurrent connections, traffic
roughly 36GB per day
* 90% POP3 (mostly pop+delete), 10% IMAP
* ~170GB of mail on disk

Current problems experienced:

* Massive load averages (>500)
* Memory exhaustion (3GB)
* Server looses network connectivity (related to massive loads)

I've got a new server ready for action, well after mail directories have
been rsync'd over. Will have 8GB of memory and much fast discs.

I'm looking at giving Dovecot + Postfix/LDA a go. From my research today it
seems that running a POP server without LDA (or without the W=(\d+) filename
field) is a futile business. I'm running Gentoo, and the stable release in
portage is currently dovecot 1.1.7, with 1.1.14 being available but masked.

Long stories short, will Dovecot with the Postfix/LDA give performance equal
than Courier-IMAP or improved (because of the cached message sizes)?

Kind regards

-- 
Kenneth Kalmer
kenneth.kalmer at gmail.com
http://opensourcery.co.za
@kennethkalmer