nothing I am aware of. Best practice is to use groups and not single users. The Office dialogs for RMS are nice but I recommend to think about using the Data Classification Toolkit and templates (http://technet.microsoft.com/en-us/library/hh204743.aspx)
to have a scalable, user-friendly, reproducable and mantainable way to add document protection.
Sorry that I do not have a direct solution for your question.
You should be able to do via Universal Distribution Groups. They will have to have an email attribute for the group.
One thing to be aware of is that the group membership cache in ADRMS doesn't refresh very quickly, so if you add and remove members a lot they may not be able to open the document right away (if they were just added to the group).
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