Our church has two email servers - an Exchange server and another email server created under IIS on our web server. The latter was done to provide email services to missionary families without having to provide a logon account in AD. Anyway, both are on our private LAN and behind a Linux IPCop Firewall. Email can be sent and received via both email servers externally; however, email could not be sent between the servers inside the LAN. I set up an SMTP connector on the Exchange server, and now email can be sent from the Exchange server to the IIS email server, but email cannot be sent from the IIS email server to the Exchange server. When email is sent from the IIS email server to the Exchange server, an NDR with status 5.3.5 is returned immediately. The postmaster message is from the IIS email server, and research tells me it is a loopback problem - not sure how it is occurring or how to fix it. Anyway, the IIS email server does not have connectors like the Exchange server, and so I am not sure how to get the Exchange server to accept email from the IIS email server. Any help that can be provided will be greatly appreciated.

Did you create another SMTP Virtual Server on the webserver? If you did, it is using the same IP and/or port as the default one. If you createdthe new Virtual Serverto try to fix just this issue, I would delete it. If you made any changes to the default SMTP Virtual server on the web server trying to fix this issue, I would undo them and setup a remote domain under the default SMTp Virtual server. IIS, SMTP Virtual Server, Domains. New domain, *.name_of_domain_on_exchange_server.whatever If this doesn't solve the issues, right click on new domain on your webserver, click on the Route domain "forward all mail to smart host". Type in the IP address of your Exchange server, but put square brackets around it. [10.10.10.10] This will make the webserver just send the Exchange server all e-mail that is bound for the domain, and make the Exchange server figure out what to do with it. As long as the "to" address is local to the Exchange server, you should not have to put in a relay entry... But.. If you get a "not allowed to relay" after doing this from the Exchange server when you send to it, add the IP address of the web server to the "allow relay" list on the SMTP Virtual Server Properties on your Exchange server. It should be on the Access tab, Relay button. Hope this helps. J.G.