A general question. How do you make bounces to work with civicrm?
Which extensions do you use, and by whom and how do you set up / handle the mail and also the bounces?
Kind regards.
Here is the documentation to setup bounces in Civi.
Also there are various third party mail providers available that captures bounces and for most of them extension are available in CiviCRM to record bounces eg Mandril, Sparkpost, Mailchimp etc
Here's a quick recipe on how to set up bounce processing:
Then test by sending a bulk email to a non existent email address and watch the job log for the 'Fetch Bounces' job. If it runs normally it should fetch the bounces - if not there will be an error message, usually because it can't open the mail box you set up in the first step.
Good luck.