Hi, > One approach here if it is practical to collect/maintain all of the > valid > recipient addresses is to build a virtuser table with a default reject > for each > domain the relay handles plus the list of all valid addresses. This is > very > efficient if you can automate the table updates or the user base is > stable. I have already written the code that updates the access file and the relay-domains file from the final delivery mail server so I think that to create a virtusertable should be simple enough, I'll check the documentation to see how to use the virtusertable in this manner - thanks for the pointer. > Another would be to use MimeDefang as the framework instead of > mailscanner. It > has an option to check recipient addresses via smtp to the delivery > servers > before accepting. You may have to write a snippet of perl to get that > right for > multiple domains (that's a feature...). This is less efficient but > works in > real time against the addresses that will be accepted for delivery. I'm not so sure that this is an acceptable overhead - the mail scanners process 2,000,000 messages a day. Thanks S.