Your software
My Mautic version is: v3.1.2
My PHP version is: 7.3.27
My Database type and version is: mysqlnd 5.0.12-dev
Your problem
My problem is: How can I identify why an email bounces? Is there any documentation that can be found in reference to bounced emails?
These errors are showing in the log:
Steps I have tried to fix the problem:
Hellho klandry1, how are you?
Have you tried this: docs.mautic.org/en/channels/emails/bounce-management
If you have any issue, i can try to help you 
Thank you I have identified bounced emails. I am getting the error of “Do not contact”. Do you know how that happens.
joeyk
4
That is not an error.
It means people don’t want to be contacted.