I have a Windows 2008 R2 domain with a single Exchange 2010 server. I have a firewall that port forwards incoming SMTP port 25 to the Exchange 2010 server. On the Exchange server, I have the default receive connector set to accept mail from 0.0.0.0-255.255.255.255. I have anonymous checked in the permissions on the receive connector.
I can send SMTP mail to the Internet just fine but I can't receive SMTP mail. I have the DNS set up by my ISP with an MX record pointing to the external Internet IP that is port forwarded the the Exchange Server.
What am I missing?