I'm no expert with act by any means, however ... I don't see how that would be possible. I know some act business's that attach audio files of recorded conversations, and or datamine conversations. The topic of "attachments" is too broad to attempt to apply some sort of encryption via ACT itself to expect it to intelligently tell the difference between, WORD, Acrobat, and audio files etc etc and encrypt / decrypt intelligently would be a MASSIVE use of resources. Specially in a terminal server environment. Instead I would recommend making an SOP (standard operating procedure) that your business follows in making encrypted files from the get go. Word, and acrobat pro offer such solutions themselves for encryption / password protection. I don't think you'd be happy with the results of ACT doing it for you (resource wise). Just my opinion. However if ACT! Created a sort of, "sandbox" for that attachments folder, that would prove to be quite useful (meaning nothing in, nothing out access, unless via act itself) however based on what I've read, I can see how all it would take would be one corrupted file to bring down and entire database, so some sort of back door would have to be implemented.
Depending on how you users are set up you can now just link the document. Only those with permission to the area the document is stored in can open it. Works well on a network but not useful if users are syncing unless they also have VPN.
