Supports use of Apple Scripts. Multi-threading for reading and writing email while downloading. Supports Mac OS 9, MacOS keychain, unicode and promises memory protection in OS X. Supports multilingual text. Plenty of preferences for customizing columns, text, reply requirements and more. Well-implemented drag and drop.
Installation is easy.
After downloading PowerMail, just drag it onto your desktop folder and launch the program. On startup, PowerMail builds a new folder for your mail called PM3 files . This folder can be placed anywhere on your desktop. You can then make an alias of the application and it will open and look for that folder. The nice part about this is that you can set up the program for multiple users on the same computer.