Java 1.5 is available in standard Mac OS X setup. This version does not support Tray icon, and DavMail uses a dedicated frame instead.

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.

Adjust DavMail settings: Getting started