- Must not have bugs which occasionally trash the mail database (this rules out any Outlook variant and Eudora).

Eudora uses standard Unix style mbox files, with it's own database/index files maintained seperatly. If an index problem is detected, Eudora repairs them in a matter of minutes. I never lost a single piece of e-mail using Eudora from 1996-2001. Only reason I stopped using it was my move to an IMAP server and a PHP web interface.