Exchange Not Sending Outbound Mail To Smarthost
Posted on 2004-04-21
I have an SMTP smarthost sitting on my DMZ that all inbound and outbound mail should be passing through, and an Exchange 2000 server on my inside network that accepts and sends this e-mail.
Inbound works fine - my smarthost gets the mail, scan it for viruses, and passes it on to my Exchange server.
Outbound mail that gets routed on the internet bypasses my smarthost. Examining the e-mail header of any message I send out reveals the IP address of my outgoing dynamic NAT address as the origin of the message, not the IP address of my smarthost, which is also the MX record host for my domain.
How do I configure Exchange to forward all outbound/internet bound e-mail to my smarthost?
I am aware of the "Attempt direct delivery before sending to a smarthost" checkbox in the Advanced Delivery options for the properties of my SMTP Virtual Server in ESM. I have tried unchecking this with the same result.
More details on my network - PIX firewall with 3 interfaces - outside, inside, DMZ. Smarthost sits on the DMZ, and has a public IP address. Its IP address is the MX record host for the domain.
For the inside interface, I am using a single public IP address for all outgoing internet requests - port address translation, dynamic NAT, whatever you want to call it. This is the address that appears on e-mail headers as the point of origin when I send e-mail out, when I'm guessing it should be the IP address of my smarthost.
I am willing to share IP and DNS info with anyone who is willing to troubleshoot with me.
Any ideas will be appreciated. Thanks.