If you are receiving an error similar to "Domain example.com has exceeded the max defers and failures per hour (5/5 (100%)) allowed" in an email bounce back, it means that outgoing email from your domain has triggered a rule in the server that will stop any further email from going out of the server until the next hour. This happens when a domain account sends out a number of emails that either fail or get deferred. If the number of failures or defers exceeds the server limit, no further emails will be processed.
If you received bounce email at 3.25pm, you will be able to send email again at 4.00pm.
