The Bat! is a stand-alone e-mail client that lets you configure and customize your inbox.
Who knows what they were thinking at Ritlabs, SRL when they were picking a name for their industrial-strength shareware e-mail client? Regardless, The Bat! gives power e-mailers not only basic e-mail features like filtering rules and POP3 and IMAP support, but also a highly customizable interface for sorting and viewing messages and managing multiple mail accounts.
Spelling dictionaries and antispam and antivirus plug-ins are all available as free downloads from the company's Web site. The Bat! will spell-check your outgoing messages for you automatically, and digitally sign and encrypt them with the included OpenPGP security module.
I like the program's clean interface and easy-to-understand icons, but I also like the tremendously detailed options lurking under the surface. The Sorting Office filtering dialog box, for example, gives you lots of control over how incoming messages are routed. A floating ticker widget that displays new mail is a slick and useful touch as well.
Full text can be found here.