There are many reasons for emails to bounce. You may have hit your per houly sending limit or you typed in the address incorrectly are just a few common reasons. The best way to find out is to submit a support ticket with the following information:
Your email address:
The email address you are sending to:
The approximate date and time it happened:
With this information we can scan our email logs. Our email logs contain a lot of information that help us troubleshoot the problem.