[Dovecot] IMAP traffic logging

[fp at onwebworx.net]

Hi! Is there any known way I can log traffic caused by IMAP sessions? 
First it is adequate to have a rough overall statistic let's say traffic 
per hour - this is easily done with iptables. But on the long term I 
also need information on account basis.

I thought of rawlogging every IMAP session and then simply count the 
filesizes. But the created logs have dropouts because dovecot doesn't 
log whole FETCH commands what is a problem.

Thanks for every idea you have!

Paul