MLP (Mail.Log-Parsing) is a script and soon-to-be script collection to make it easier to extract useful information from
/var/log/mail.log as produced by postfix setups like our Mailhaus.at.
Tracing emails with only grep is difficult because the major properties of a single mail, like sender, recipient, and message-id, usually are distributed over multiple lines.
mlp-findmails makes this task a one-liner. and extended it quite a lot.
Some core parsing lines are based on http://www.perlmonks.org/bare/?node_id=444335 but I have built lots of new functions and options around them.
mlp-findlogins allows helps to i.e. trace typos of user who "can not get my mail and have not make a typo".
mlp is of course available via our debian repository deb.clazzes.org.