Seriously so many issues, Not sure if its mybb or my hoster. It cannot send any mail if someone registers or even private mail, and more mailing options, it only sends if they have gmail, I have spoken to my hoster, GoDaddy they have no clue what I mean so can anyone atleast help me fix this thanks
This problem is not related to MyBB.
This is problems of your webhost service provier.
Which mail handler you use? PHPmail or SMTP?
Also, check "Add message ID in mail headers" option in Board Settings. And enable full logging (Log everything) for email fucntion. Then see outgoing email logs.
A lot of email problems can be resolved by switching to SMTP and using a relay. The IP of your shared hosting server might be on a blacklist due to someone else's abuse.