If you need to move your email to another system, or export it from our server for any reason, the simplest way to do this is via the webmail (squirrelmail) system.
At the bottom of any folder display in webmail is an “Archive” button, which lets you download selected messages to your computer. If you want to download the entire folder, you should first choose “show all” and “toggle all”.
By default the messages are exported as a zip file of EML messages, but you can change this in the Options page under “Archive settings”. The most common format for unix systems would be “Mbox” format.