I'm fairly new to exchange 2007 and I'm having a small problem that I can't figure out. I've got an exchange setup that's working fine in most respects. Over the weekend I added a new relay connector to enable an application to relay smtp emails through the exchange server. Because I already have a receive connector set to listen on port 25 I created this new connector to listen on port 26. I set the application (which is a web app) to connect to the exchange server on port 26 and it seemed that everything was working fine. However, when doing some more tests I noticed that emails sent to hotmail addresses weren't being received by the hotmail account the email was sent to. The strange thing is that the email just seems to disappear into thin air. The email doesn't go to the junk folder, theres no NDR - just nothing. Checking the message tracking logs on the exchange server and everything looks fine. Now, if I send an email through outlook, which in turn is connected to the exchange server then emails to the same hotmail recipient arrive safely. I've got reverse dns entries set up for my external ip address and domain name, and they check out ok. So far, emails sent to other addresses seem to get there but my main concern is that if they're not getting to hotmail then there could be other addresses they're not getting to. I've set up SPF records and emails arriving at non-hotmail destinations have SPF-Received: Pass in the header. Any ideas what's going on here? Thanks,