SendmailAnalyzer as is name suggest is a free Sendmail/Postfix log analyzer.
It process maillog files and generate dynamic statistics in HTML and graphical
output. The reports are generated in real time so that it let you know at any
moment what is going on your mail servers. It use time (hour, day, month and
year views) and cross-linked navigation for easy use.

SendmailAnalyzer is easy to install and highly configurable to match the
dozen of Sendmail possible configurations. It also support report for all the
major milter or sendmail filters like SpamAssassin, MailScanner, Clamav,
Amavis, RBL check, J-ChkMail, etc. SendmailAnalyzer is really helpful for
IT reporting.

Collected data are stored in flat files that are automatically archived or
delete to keep disk space. All reports before the current day are cached to
save system resources and are displayed in less than 1 second.