Pubblog MailSteward Pro v11 Mac OS X
 

With a single click on the Archive button, MailSteward will go to work storing copies of all your e-mail from your Apple Mail or PostboxT mail accounts -- including full text, HTML and attachments -- in a relational database on your computer for fast, multi-term searches and easy retrieval.
MailSteward has a wealth of features for importing, tagging, saving, and exporting your vital e-mail information in a number of standard data formats.
* archive over 1 million msgs
* export and merge databases
* schedule auto-archiving

Home Page - http://www.mailsteward.com/