CPGNuke Email Bounce back!

Problem: Emails that my site (which is on CPGNuke [a flavor of PHPNuke]) get bounced back because - (I believe) the sender is "". I need someone who's an ace at PHP, is familiar with PHPNuke or CPGNuke and phpBB and who is also a wiz on email (in particular EXIM) to trouble shoot, fix, and tell me what was/is wrong. I've attached screen shots of the messages I'm getting and of the files which need edit. Thanks in advance for your prompt attention SITE INFO: Running WHM and cPanel PS I need someone quickly, as my site does not function without the ability to send messages generated by its scripts) We are a profitable site and will require additional help - so we are looking for someone we're comfortable with to help with multiple tech projects.