Postmaster addresses


I’ve got a problem with bounce-back mail being sent to the wrong postmaster address.

I have two domains, lets say and, hosted on the same account at DH. The problem i have is that bounce back messages, joomla mass mail function with some users that have no longer active email accounts, from domain get sent to even though both hosts have their own postmaster addresses.

Any ideas what the problem could be or how do i rectify this problem.