EMail header has wrong address

[ATForum]

So evidently when the forum was set up someone typed in a wrong email address for our email address. instead of .org, they used .com. We noticed this because when people register and they get an email from the forum the email address in the email is wrong. They try and reply to it and get the no address found error message.

Any idea where in the admincp I could find this and fix it?
You guys rock you've been so helpful so far. Appreciate it!