Maigret for Mac

From Hyperbolic Software:

• Maigret is a plugin-based application that allows for rapid searches.
• The actual release comes Mail Search: a plugin that allows you to search the contents of any e-mail stored in the commonly-used canonical mbox format.
• Automatically, Mail Search manages the mailboxes of the most widely used e-mails applications, like Mail, Eudora and Mozilla.
• Mail Search is very simple to use, open the application, type the word to search for and click on the search button. That's it!
• If you use another e-mail application that does not handle e-mail directly in the mbox format, you must export them in the right format first and then add them in the list to search.
• Mail Search also allows you to search using regular expressions patterns.