In our LAN, we have a development box with IIS 7 that has an SMTP Virtual Server installed. All development applications send outgoing mail to this virtual SMTP server, and it in turn relays the mail to our internal Exchange 2007 server. Or, at least it used to. Our network engineer recently replaced our Exchange server with another one, and now the mail is no-longer relaying.
Strangely enough, in our production environment, we have a similar setup. All outbound mail is sent to a virtual SMTP server (same version of IIS), and that server relays mail to the same Exchange server, only over the Internet. And outbound mail is working from the production environment. I've tried mirroring every single setting on our development box, including changing the smart host to the Exchange box's Internet-facing host name, and mail continues to linger in the queue.
The development box is able to successfully resolve the smart host's name, and I can connect to the Exchange server via port 25 from that box just fine.
Being completely unfamiliar with Exchange and weakly familiar with SMTP, I'm clueless as to how to troubleshoot this issue. The network engineer hasn't been able to figure things out either. What could be causing this to not work?
Here's my Virtual SMTP Server settings.
- Under the delivery tab, Outbound Security dialog of the SMTP server, "Integrated Windows Authentication" is selected, and a valid username & password is entered. The user name is prefixed by the Windows domain (domain\username). TLS encryption is selected.
- Under the delivery tab's Advanced dialog, we have the following settings:
- Masquerade domain: mycompany.com (I've tried removing this to no avail)
- Fully-qualified domain name: mycompany.local (I've also tried mycompany.com)
- Smart host: myexchangeserver.mycompany.local (I've also tried its public domain name)
- The direct delivery and reverse DNS lookup options are disabled
As far as Exchange settings go, I'm not sure what to look for, but I have access to the box and can post its relevant settings if necessary.