Sorry, I guess I didn't explain too well. What we (both) had was a 'first mail rejected, please resend' type system. But my understanding of the Argosoft system is that while the resend could be automated, normally it is not, and the original sender has to resend by hand. I'd just turned mine on, so it caught out my secondary who I've had no problems with previously, his was on for some time, but didn't know about spamcop.net till I told him. Between us we'd managed to render passing your confirmation coded mail from my secondary server to my own, primary, server, impossible. Whatever, I have decided NOT to use the Argosoft implementation of grey listing, since I believe it can lead to loss of mails from legitimate automated senders such as forum passwords and the like.