Exchange 2010 Signature Policy per group

Exchange 2010 has this functionality already baked in. It's not entirely based on permissions like AutoDL sounds like it was, but I would argue it's comparable.

For each distribution list you can set group owners and set the membership type of the group to any one of the following.

• Open. Anyone can join the group without being approved by the group owners.
• Closed. Members can only be added by group owners. All requests to join will be automatically rejected.
• Owner approved. Group owners must approve or reject requests to join the group.

Similarly, leaving the group is either "anybody can leave at will" or "group owners must remove users".

Auto Archiving is a client feature and thus you'd need control of the clients to turn it off. With that being said, if your hope is to just store everything in the mailbox instead of an archive, you'd be better off disabling the ones you can via group policy and sending a notice to all as to why they no longer need to auto-archive.

Assuming you're trying to purge data, and not let them archive, like i said, that will be tough for unmanaged clients.

Edit 1:

I stand by my original post but have some more info to add. First, i think this is more of a policy issue than a technical one so to speak. I realize of course that policy enforcement is easier said than done. Second, as i stated manage the ones you can and notify the ones you can't.

Now for some other ideas, you could put in some protective measures since i don't know of any preventive measures.

1. If you're running exchange 2010, you can extend the time of the recycle bin. Just be mindful this will grow your store. http://www.simple-talk.com/sysadmin/exchange/single-item-recovery/
2. Actually archiving everything could help as well, something like a Symantec e vault, Depending on which solution you use, this could also help to reduce the size of your mail store.