Automatic Email Signature

Looking for a system to automatically add email signatures, with the following features - 1. Multi format - html, text 2. Linked to data in Active Directory 3. Users able to view signature prior to sending 4. The signature appears on the file copy in "sent items" 5. "send as" - signature is based upon the details in the "from" field - not the person logged into the network 6. 75 users on network (MS Exchange) Could be an add-on? to a packaged product.