Older OSX releases include Java 5, this version does not support Tray icon, and DavMail uses a dedicated frame instead. An upgrade to Java 1.6 will enable tray icon. Recent OSX versions either include Java 6 or can install it automatically on first Java application launch.

Download DavMail Mac OSX package from Sourceforge:

Safari should automatically extract the application archive. If not, just double click on the zip file to trigger decompression. The extracted DavMail.app directory is then recognised as a valid OSX application.

Just double click on the application icon to launch DavMail. On first start the application displays the Settings (Preferences) frame.

In order to get balloon notifications, you will need to install Growl 1.2.2 from http://growl.info/:

Adjust DavMail settings: Getting started