I have just installed POSTFIX on a Debian box, I pointed the relay host config setting to an exchange server which will deliver the mail to external users. So what I am trying to do is telnet to the debian box and send an email to [email protected] which will then be past to the exchange server for delivery. The problem is I get the following: rcpt to:[email protected] 554 relay access denied I have seen a section in the config "mydestination" but i want the exchange server to decide which domains it will deliver for and not the POSTFIX server.