Mailrep - A program for reporting mail log information in sendmail and postfix.

A program for reporting mail log information. You can configure it to respond 
to errors in various ways and you can specify RBLs that can be used for 
blocking spam. The program can measure the number of messages sent for a 
particular account and the number of messages that the server processes daily.

WWW: http://experience.bsdnetwork.org/