I think when they are about 11 or 12 years old, they can have e-mail.
You can always keep their password for them and check or use a program to watch them wheile they are surfing. They have a lot of programs that you can put on your computer that can't been seen by users on the computer.
when you are ready for them to have a life. I got email when I was 13. I think any younger and you're being ridiculous. I think the only thing you should block is porn. Kids are curious, want to learn about what their bodies are doing and why they are feeling the way they do. You gotta back off and let them figure a few things out for themselves. Just make yourself available for questions, and try not to make it embarrassing, which it becomes as soon as you laugh (the nervous laugh), make it matter-of-fact.
since we are moving I plan to give both my girls ages 11 & 8 emails so they can keep in touch with their classmates they are leaving behind. I am nervous but as Queen of the Click mentioned I do plan to keep their password and monitor what they are doing.
my son got his at 13yrs old he will almost be 14 and has a myspace and messenger. But i check everything he does. he also tells me everything. i am his frien on my space that way i can check on him. told him he better make i do not see any %^&* on his page.... . he is resposible now. so i would say email 13 other stuff depends on kids and parents trust on kids...