mboxgrep is a small utility that scans a mailbox and displays messages matching a basic, extended, or Perl-compatible regular expression. It supports mbox, MH, nnmh, nnml, and maildir folders.
Information regarding Project Releases and Project Resources. Note that the information here is a quote from Freecode.com page, and the downloads themselves may not be hosted on OSDN.
Crashes which occured upon reading of MH folders have been fixed, as well as a potential problem with mbox and maildir folders with the same cause. MH and maildir backends no longer read files which are not RFC 2822 messages. The ability to read gzip compressed mbox folders from standard input has been added, too.
