Automatically creating a forwarding email address that matches a new sites subdomain.

I would like to be able to automatically create a forwading email address that is user selected or matches a new subdomain when a member creates a blog (most likely with Pro Sites) Doing it with the Membership plugin as a user selected forwarding email would be fine too, maybe even preferable.

It has to be automatically generated upon successful signup or Pro Site Package selection.

If you know of current plugin or method for doing this please let me know. Otherwise I think it would make a great WPMUdev Plugin.

Example: New Site = johnsmith.webdeveloper.com -> johnsmith@webdeveloper.com

johnsmith@webdeveloper.com is automatically forwarded to their signup email. (or a users selected email address and modifiable at a later time would be an excellent option)