Stay Away !!!
Here's a direct quote from the "writers"
Intermesh does not support the community version in any way! If you want support you contact Intermesh for the Professional version and get support.
That just goes to tell you how much they stand behind there product. Which they don't. They've got poor MIME support, File upload modules doesn't work, There php coding skills are extremly poor. I mean there so called module addon's are just drop in and install as they claim. In order to use Other modules that otheres have wrote you must hand edit there theme file (ALL there theme files) Else you can't have a new module have a icon in menu bar.
In my option I'd avoid this produce and stick with Squirrelmail or another type of groupware.
Version in Question : 2.05 and CVS