I remember years ago EX was able to do it but then design was changed to not to do it (could have been many reasons I could think of) and now it needs manual intervention to dispose data that is out of retention.

EMC has new Email Archiving product called SourceOne, that seems to have this capability. You might want to discuss it with your account team in EMC about your new requirements. I am sure account team will be able to get you right answers after checking your requirements.

Regards,
Rajan