vQuiz Not Sending Email in Joomla Backend

Also, I checked my email and it is receiving email from other email client server. So it is not my email problem. I also checked after I have completed a quiz and then input my name and email address to obtain the Certificate and it is sending out the Certificate fine.

It is just the Joomla backend is not sending out the Certificate. I have double checked this already.

Hello Support,

After a subscriber has taken the quiz and passed the quiz, they can input their name and email to obtain the Certificate. Once an email has been sent out with their Certificate, the manual "Send Certificate" in the Joomla backend is supposed to allow me to resend the Certificate, however, when i click on resend, it said email send successfully, but I did not receive the email.

Is there a limit that was set to only allow the Certificate to be sent one time only?

Please advise, how can i fix this problem.

Thank you.