Isoqlog is an MTA log analysis program written in C.It designed to scan qmail,
postfix, sendmail logfile and produce usage statistics in HTML format for 
viewing through a browser.It produces Top domains output according to Incoming,
Outgoing, total mails and bytes, it keeps  your main domain mail statistics 
with Days Top Domain, Top Users values for per day, per month, and years.

Features:
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* Multi MTA support(qmail (multilog and syslog), postfix, sendmail, exim)
* Multi-domain support: Shows quite detailed statistics for not only your main 
domain, but also, any domain you want.
* Displays statistics for common mail delivery errors.
* For each domain you specify; displays Top incoming, outgoing, total and byte 
based statistics for users.
* Displays server's activity based on incoming, outgoing, total mails and size 
of incoming mail, for domain  and its users.
* All days', all months', all years' activities ( above ones ) are stored for 
future inspection.
* Multi-language Support (17 languages supported as of isoqlog 2.1.1!)

WWW: http://www.enderunix.org/isoqlog