Sorry if I don't have a lot of details but just wanted to put this out here to see if anyone might be able to point me in the right direction. We are running exchange 2000 server and we also have gfi mail essentials anti-spam and a watchguard firewall. One of our business partners is saying that they are having problems sending email to our primary address because they are getting invalid character type message, something about /r characters and they don't allow it to fail to the secondary smtp, which from what they explained sounds like our isp's address. They say that we might not have noticed this with anyone else because most people aren't that strict and let it fail over but they don't. I never even realized that we had a secondary smtp so I am confused and everything goes through our firewall which only routes the one address to our smtp server so I can't see how if can be come through a secondary one? I tried looking at our firewall, anti-spam and exchange but don't even know where to start and they aren't being very helpful. Sorry that I can't be more specific but I'm just hoping for someone to point me in the right direction. Thanks, Joe