Default email domain

I have this situation:

  • there are 2 domains added to cyberpanel domainA and domainB
  • when there is an error of sending mail from domainA (let’s say to a wrong email address and the error is “Undelivered Mail Returned to Sender”) the user gets the error from the domainB

as if there is a smtp default domain that sends all the errors.
How can it be corrected so the users from domainA get errors from domainA and users from domainB get errors from domainB

This error happend to me on multiple instances of Cyberpanel on VPS servers.

can you please show me the results of checktls for both