Thanks for the response...
It appears to be something with the mailserver....
I created a emailtest.php to call it in a browser from my url AND it did NOT work.
So for about two days now...my host is looking into this. Very frustrating.
Ok if i had to guess something is up with your mailserver. you can try to set up another email address from your cpanel after it is created and you know it works. open yoursite.com/inc/header.inc.php and change your email address to the new one save the file and try the invite a friend again. not saying this is going to fix it but worth a try.