Oh, ok.
I have thought of bringing back the supporting membership thing, and an email address would be a possible incentive, but with the number of useful, easy email accounts out there (gmail), it's somewhat pointless.
Basing it on a users name would be a cool feature, but the user can change their displayed name at will, so it would have to look up their login name.
If you simply send someone a PM, it will (by default) send them an email as well, which is similar to what you suggested.
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