#1 son is of an age where he would love an email address. There are many pay for services that offer safe kids emails, but it seems like a dumb thing to have to pay for.
The must have feature is an exclusive whitelist. This means that ONLY people on your contact list can send you emails.
My beloved GMail don't offer this service, but Microsoft's Live Mail does. I will let you know how it works out. It took a while to make sure all the permissions were locked down.
Incidentally, the default account name for my location is live.co.uk or hotmail.co.uk, which is lame, so I experimented with the URL and found I could trick it into US mode like this: https://signup.live.com/signup.aspx?mkt=EN-US&rollrs=12&lic=1. This gives you the option of registering for live.com or hotmail.com addresses.