Anybody know how to do a search on Active Directory or Exchange for all accounts that have mail forwarding set up?

I haven't seen any field that looks like 'forwarding' in the list of fields that you can search on in the Active Directory search.

I would like be able to turn mail forwarding, auto replies, and Out of Office responses off, but first I would like to find all accounts that are sending such stuff.

Some background - I just installed GFI Mail Essentials as a spam filter and noticed that a lot of bad addresses were being whitelisted. The way GFI Mes works is that it uses all outbound mails as examples of 'ham' - good, non-spam, mail. So the only way for weird addresses to get into the GFI whitelist would be for spam to be being forwarded by various users.

So I decided to shut off mail forwarding, auto replies, and Out of Office responses on the Exchange server and see if that would prevent the addition of bad addresses to the whitelist.

It appears to have worked, but I would like to know whose mail forewarding I just killed