actually, you can do it only when they are near expiration, not after, as their subscription is deleted from their status...
Under Subscription Manager in the admin cp one can list all Completed " expired " subscriptions... Unfortunately that is all one can do. I was hoping there was a query that i could run that would grab all those expired users and possibly even move them to another usergroup, and then i would mass mail that usergroup.
For them to show up on that completed list there must be some setting that distinguishes between expired and not expired..