I doubt that requiring email confirmation would solve the problem. It's not difficult to create a new email account!
Unfortunately the only suggestion for a solution that I can think of might well be very unpopular. It would involve changing the way players are charged to use online Dominion such that there were three categories of user:
- Able to play using base set against bots only. Free.
- Able to play against human opposition (just like the current free subscription) for a small one-off payment, maybe one or two euros.
- Silver and gold subscription as at present, but perhaps with the first subscription bought being discounted by any one-off payment that has already been made.
That should discourage people signing up merely to ruin other people's games.
To avoid upsetting existing users it would probably be wise to have the above apply only to new users. That would leave us with the existing morons, but once they'd been banned, they would have to spend money to get back in, so presumably wouldn't.