Notification emails not getting through to recipients.

My colleague was receiving notifications emails from a few forms two weeks ago and lately the emails have not been getting through to his Outlook inbox. Our IS team looked into the issue and they could see anything on our end preventing the emails from coming into our Outlook Server.... 

Please provide us an email address of your colleague or the form ID that is not sending the Email Notifications. 

You can also check if the email address of your colleague is in the bounce list. 

How to Remove Your Email Address from Bounce List