SBS 2011 external postmaster address

Hi,

I am running SBS 2011 Standard and migrated from SBS 2003.
When an email is sent to a non existant user the reply comes from my Directors email address. I have changed the setting using EMC and EMS, both show the external postmaster address as postmaster@"mydomain".co.za.

I have searched on the net without any success and so I turn to you, any help would be much appreciated.

Thanks!

anyone? please help!

It could be that the message in the queue might have expired, so try suggestions given in this following article - http://support.microsoft.com/kb/284204