IMAP Traffic not counted ?!

[bodysplit]

iptables will only be useful for server-wide statistics. Like awstats for www, one would need a loganalysis tool like isoqlog to analyse per-domain or per-user stats.

I have never tried using awstats for maillog analysis, although the awstats-team claims it works. Perhaps one can check that out. After all many will already have awstats installed for HTTP analysis.