The Bat! is an e-mail application that features support for multiple POP accounts, true multithreading, MIME and UUencode standards, message notification, PGP support, APOP authorization, message sorting, message templates, minimization to the system tray, and multimedia support.
Features :

Mail Filtering

You wish to toss messages from your friends into special folders, send automatic replies to people from other departments, mark messages from your dear ones with special colours...

Press Ctrl+Shift+F to quickly create a new filter based on the current message and define its functionality.

Templates

A sales manager should send personalised price lists and promotional material to her/his company partners.

Just create Quick Templates by pressing Ctrl+Shift+Q, type the handle of the template you need and press Ctrl+Space - The Bat! will promptly insert text, attach files and make the message ready to send.

Virtual Folders

A technical supporter should find all messages from/to a particular person for a specific time period.
Press F7, specify your search criteria and folders to look in, start...

To keep search results all together for further references, create a Virtual Folder.

Spam filtering

Every day, you have to go through endless lists of messages from somebody who wants to sell you something you don't need?

You want to read messages only from people you need and do not waste your time reading all those ads?

Just add BayesIt!

anti-spam plug-in to The Bat!, feed it with examples of spam you receive and relax - BayesIt!

filters our virtually all unwanted mail while messages you need get through

Download The Bat 3.71.03