I chose Gmail because its got really good spam filtering, and there is a setting in there that forwards me a copy of every email they get.
This combined with filtering software on our home PC, and education about online safety (regarding info they can give it, and who they can converse with) is about the best I can come up with. I dont want to be so restrictive as to have a whitelist only system - or they will just figure out they can open a webmail account themselves.
I want my kids to have a good working knowledge of the internet and email, and all the ettiquette, rules, advantages and dangers involved, so they can help themselves, rather than have me try and control every little thing they do.
What do other Geekzoners do for their kids??