From the gut feeling I would vote "no", but i would be interested in hearing why you think this restriction would be a good idea?

Btw: I have no idea from which server on which continent my email pops out of Google network. Same applies to some of the other systems/addresses I use, so what you propose as how to limit the user group is very inaccurate indeed. To restrict the user community the way you propose requires manual verification, and wouldn't be very accurate even then.