All things in perspective. Its never been a major issue (and still isn't really). All that's happened is that his email has been recieved. He won't have anyones actual email address. No real harm done and it livened up a dull day.
I would think that not allowing newly joined members access to the Members area for a 30 day period would be all that is needed. When these people can't contact anyone immediately they will quickly move on and forget about it. But if a new member wished to post they could.
Nothing will ever be completely secure. I believe that hundreds of hackers attack the Pentagons computer each and every day, and some actually get so far in! Now thats scarey!!!
Generous George has obviously taken on board, but not fully grasped another of Groucho Marx's quotes:
The secret of life is honesty and fair dealing.. if you can fake that, you've got it made.
I think he'll need a lot more practice before he becomes much of a threat!