I was able to see the email address of a member who sent me a PF email in August. I don't think he wanted me to, considering how hostile he had been. The email I got was from <username>@physicsforums.com. It looked like this:
This is a message from <username> at Physics Forums ( http://www.physicsforums.com/index.php ). The Physics Forums owners cannot accept any responsibility for the contents of the email.
To email <username>, you can use this online form:
http://www.physicsforums.com/sendmessage.php?do=mailmember&u=<user id number>
OR, by email:
mailto:<his email address at a university in germany>
This is the message: