I currently have my Postfix system set up to forward any email to mydomain.com to my mail server. However, sometimes I get emails to an unknown address. When this happens my mail server replies back to my Postfix server with unknown host. After this happens, I keep getting the following message in my mail log:

postfix/qmgr[1820]: warning: connect to transport smtp: Connection refused

I'm not sure who my Postfix is trying to connect to, and I constantly get these messages until I go into the mail bin, find the message, and delete it. Is there anyway I can configure Postfix to just drop the email if I get an "Unknown recipient" response from my mail server? Any way I can figure out what my PostFix system is trying to connect to? Thanx in advance.