Get the Most Out of Eudora
Eudora is a classic, powerful, flexible and efficient email client that cans spam precisely, too, and shows nary a weakness.
Backup E-mail fully backs up all messages, contacts, rules, accounts, settings and more from most email clients in an easy to use manner. (Windows)
blinkx finds emails and local as well as web content fast. You can search explicitly, but blinkx also provides a toolbar that automatically finds content (more or less) relevant to what you see or write.
Enfish Find lets you search, find and preview emails and attachments in a comprehensive manner.
X1 lets you find text in emails, contacts, attachments and files fast.