On Sat, 2012-06-23 at 07:04 +0200, Emmanuel Dreyfus wrote:

Hello

I am having a hard time with users using POP while leaving mailboxes of several gigabyte cumulated. This causes a lot of disk I/O and kills performancs for everyone. I try to encourage people migrating to IMAP, but that migration will take some time, and therefore I am looking for alterantive ways to workaround the problem.

What mailbox format do you use? This shouldn't be a problem with for example mdbox, probably not with sdbox either and with mbox/maildir there are settings that can improve this.

Or are you not talking about opening the mailbox, but about clients redownloading all the mails all the time?

I found pop3-throttle-plugin.c, which seems a smart way to solve the problem, unfortunately it comes with no documentation. I was able to build it and load it, bu itsays nothing in the logs. Is there any doc somewhere? Any advices on how to set it up?

It's about allowing clients to see only X new mails per Y time. But I don't see how that would help with your problem if that's related to old mails.

Anyway, quick docs:

"touch /etc/dovecot/pop3-throttle-enabled" to enable the throttling

plugin { pop3_throttle_max_msgs = 10 pop3_throttle_max_kbytes = 1024 }

Which allows a single user to see max 10 new messages or max 1 MB of new messages per 15 minutes, whichever limit comes first. After 15 minutes more messages become visible again to reach the limit. The 15 minute limit is configurable by recompiling:

#define POP3_THROTTLE_STATE_RESET_SECS (60*15)