Grepmail

Search for emails in a normal or compressed mailbox using a regular expression or date constraint.

Features:

Gzip, bzip2, tzip support
Piped input supported (compressed or not)
Supports complex dates like "between Jan 15, 1999 and 5 weeks ago"
Can ignore non-text MIME attachments
Can search only the header or only the body of an email
Can recurse subdirectories
Automatically optimizes for speed vs. flexibility when searching based on date constraints.

Links:

Download most recent version (5.3033)
Change log
Get the code via CVS
See the todo list.
Register to be notified of updates
Join the users and developers mailing list
Visit the public chat forums: Open Discussion, Help, Developers
Report a bug, or submit a patch
SourceForge project page for grepmail

grepmail has been integrated with several mail readers:

Also check out Jeremy Malcolm's gtkgrepmail, a graphical front-end for grepmail.

Author and Maintainer:

David Coppit <david@coppit.org>, http://coppit.org/

Thanks to SourceForge.net for the project hosting and management.