[PERDITION-USERS] filter with gnupg processing

Hi I checked the documentation of Perdition and I am not sure if the following scenario can be implemented. A Client (e.g. Outlook/TB) connects to a Perdition imap/pop proxy. The proxy itself connects in turn to the real imap/pop server using the credentials provided by client (possible switch of user_name). Before an email gets delivered to the client, it will be processed by a filter program which does some gpg processing (sig verification, decryption), which is fully transparent for the client. Can such a scenario be implemented with Perdition (ideally I would like to write the filter program in perl :-) ). Thanks, Mike