Something else to bear in mind is that emails don't always reach the intended recipient - this is a particular problem for Hotmail (and other Microsoft) addresses, because the emails can disappear into a black hole. Yahoo generally bounce back messages they don't like; Gmail put them into spam. Gmail users should check the All Mail folder from time to time.
This isn't just an issue for your emails going to the other person, it could also apply to their replies to you (depending on the email provider you use). If all members followed my advice and deferred exchanging email addresses until they had established a rapport with their new relatives there would be less opportunity for things to go wrong.