Our new file storage feature is currently available on the beta server for testing. To access it, just go to http://www.fastmail.fm/beta/ and login with your normal account details and click on the 'Files' link at the top of the screen.

Some more details and feedback are available on our forum here: http://www.emailaddresses.com/forum/showthread.php?s=&threadid=17542

A limited FAQ is available here: http://wiki.fastmail.fm/wiki/index.php/FileStorage