Thunderbird makes e-mailing safer, faster, and easier with such features as intelligent spam filters, a built-in RSS reader, and quick search. Thunderbird was designed to prevent viruses and to stop junk mail so you can get back to reading your mail. Thunderbird provides effective tools for detecting junk mail. Its tools analyze your e-mail and identify those that are most likely to be junk. You can automatically have your junk mail deleted or you can put it in a folder you specify, just in case you like reading junk mail.

Evo Networks recomends Thunderbid as the best alternative email client to Outlook (windows), Entourage (outlook for mac), or Mail (mac) if your firm want's to standardize across the organization with email clients. This is assuming the firm is using only a simple IMAP or POP3 email server. If your firm uses exchange, Outlook and Entourage are your best bets. Download Here.