Hi Peoples, I am implementing RedHat Enterprise Linux in an existing Exchange environment. I will be using Postfix for front-end mail handling, here is what I would like to achieve; when am email comes into postfix it will verify with Active Directory via an LDAP query if the user/account exists (this part is functioning perfectly so far) and if it does then the mail is delivered to an existing Exchange mailbox, if the user/account does not exist in AD I want Postfix to check local recipient tables for local delivery so some users can POP the mail at a later date using Cyrus (or similar I've not decided as yet). As I said – I have the LDAP query functioning fine at this point, but if the user does not exist in AD I get a 550 error where I would prefer some local recipient lookups to occur. I’m sure that this must be possible – I have tried a few solutions but none have had the desired result.. Thanks in advance… Matt.