Thunderbird is a free email application that's easy to set up and customize

Thunderbird is a great email client from the same people who brought you the Firefox browser. Thunderbird gives you IMAP/POP support, a built-in RSS reader, support for HTML mail, powerful quick search, saved search folders, advanced message filtering, message grouping, labels, return receipts, smart address book LDAP address completion, import tools, and the ability to manage multiple e-mail and newsgroup accounts.