[Kolab-devel] [issue1101] Kolab pop3 serious problem on high number of users

Fabio Pietrosanti / Khamsa SA kolab-issues at intevation.de
Thu Feb 2 12:37:53 CET 2006

New submission from Fabio Pietrosanti / Khamsa SA <kolab at khamsa.ch>:

If you have a high number of users pop3 would hit serious performance problem.

The default cyrus configuration allowed the users to use apop.
This seriously impacted system performances leaving the system into a unusable state with 3000 
concurrent pop3 connections on a dual XEON 3.2ghz with 2GB of ram.

The uptime was reaching 40.

The problem was identified and fixed as described by the following document:


I think that APOP should be disabled by default because of POP3S support.
SSL/TLS it's not performance problematic.

After setting up in imapd.conf:
allowapop: 0

The system uptime lowered to 0.5 and pop3/pop3s start responding and working immediatelly.

I also found a lot of little other things that could be tuned and will submit for each of them an issue.

messages: 6430
nosy: khamsa
priority: urgent
status: unread
title: Kolab pop3 serious problem on high number of users
Kolab issue tracker <kolab-issues at intevation.de>

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