Keep your mailboxes to a reasonable size.
Version:Email Archiver is an AppleScript Studio application which sets up 'archive rules' for keeping the size of mailboxes to a reasonable limit. It allows you to specify which mailboxes you want to archive, how old messages must be to archive, and how often to roll over archive mailboxes. It currently works with Mailsmith, a version for Eudora and Apple Mail is underway.
Operating System: Mac OS X