I had 2 issues with Ninja forms (email confirmations not getting to me & submit button taking too long. Turns out neither was a Ninja forms problem. Ninja forms even signed onto my site and couldn’t find any issues to cause the long delay after pressing submit. Here are the solutions:
Problem 1: Forms taking too long
Solution: From my hosting company – our servers are now being setup with outbound spam filtering enabled to try and limit how much spam an exploited email/web account sends out – this is to help avoid getting listed on RBLs and stuff which can take days to get deslisted. The filtering is what is adding the delay to your form mailer since you’re sending the emails to a remote address. The sendmail function completes after the spam filtering check is done. We will turn off spam filtering for outbound emails. That would get rid of the delay.
Problem 2: Email confirmations not getting to me
Solution: I was using Google apps for my domain email and the cpanel settings were treating my emails as internal and not forwarding them. Once they made a change the emails forwarded to the domains MX records which pointed to Google, problem solved.
Hope this helps because I was tearing my hair out thinking Ninja Forms was broken. I installed Contact Form 7 which acted the same way which is why I knew it was a server issue.