Eudora

EMail Fat Client that I used ages ago.

http://en.wikipedia.org/wiki/Eudora_(e-mail_client)

My favorite feature

• when filter threw an email into a folder, that folder would open in a new window - this is great for getting your attention when you have new messages in 10 out of 100 folders (though a reasonable alternative would be to let you sort your list of folders by number-unread-msgs)

• could have a Reply automatically stuck into same folder as the msg you're replying to

At some point (during Qualcomm ownership) they had a "free" Advertising-supported version.

Eudora was developed by Steve Dorner in 1988 as a part of his studies at the University of Illinois at Urbana-Champaign and was acquired by Qualcomm in 1991.