Notification email not sending after submission

After submission of our application form, the Autoresponder email sends and the Thank You page appears but the Notification message does not send.  I have checked our inbound email security appliance and there is no sign of it trying to come in.

Hi, 

Your email was in our bounce list. This happened because your mail service provider was rejecting emails from us. I have removed the email from the bounce list, so it should work now, and you should be able to receive emails normally.

For future reference, please follow the guide below which will show you how to check and remove yourself from the bounce list:

How-to-Remove-Your-Email-Address-from-Bounce-List

Also, please refer to the link below for tips on how to prevent this issue from happening in the future:

How-to-Prevent-Email-Bouncing-Related-Issues

Thank you!

Thank you for your help.  We've added this to the whitelist and it's working great now.