Google group type plugin

Is there a “google groups” egroup type plugin.
Currently all my site’s members discuss stuff via google groups. this is traffic that could be added to my site. is there a plugin that does just about the same basic functions of allowing people to discuss stuff and recipients to the list receive a daily digest or direct email etc, perhaps the other features too; file upload and wiki style editable pages.

I’ve tried BuddyPress which i think would be great for the future but it’s just too much for my needs.
All i want is a simple discussions group.

it may exist but i can’t find it.
thanks
Shane