We've recently begun switching from using a 3rd party hosted POP3 service for our email to using our internal Exchange 2003 R2 server. We have a TrendNET firewall that is forwarding port 25 to our server. We have also modified the MX record to point to our static IP at our office.
What's odd is that a DNS report from DNSstuff.com shows that the mail server is allowing a connection test and shows the custom SMTP response banner I created as a test. However, when I telnet to our IP on port 25, it never connects. I downloaded and ran PortQry.exe (MS article 310298) and it shows the server as listening.
There's definitely an issue somewhere as email is not being accepted. Sending email from the Exchange box works, but is strangely slow.
Any hints would be appreciated.