Currently if the sender wants to automatically delete (expire) the message from recipient mail files after specific date/time, then it is not possible to do so.
The current option for setting expiration date in "Delivery Options" while sending mail, requiers an archive criteria to archive those expired documents. It does not automatically delete those expired documents from mail files.
So there is a feature request to provide such option where sender can select to remove the mail from user mail files after specified date/time.
This Enhancement request is submitted for Domino Server version V10 and V11.