I am using Windows Server 2003 and Exchange Server 2003. Exchange Server is running on the domain controller as is our VPN. Everything seems to work perfectly except I cannot connect to the Exchange SMTP server from outside the LAN.
Inside the LAN:
-I can telnet to port 25 on the server,
-Thunderbird will send mail to the Internet through the exchange SMTP server independant of our ISP’s SMTP server (i.e. Thunderbird’s outgoing server is 192.168.0.10 and header does not indicate the the mail went through the ISP’s server),
-Mail sent between users on the LAN never leaves the building.
Concerning the WAN:
-The router is a Linksys WRT54G,
-We have a static IP.
-Port 25 is forwarded to the private IP of the Exchange Server (192.168.0.10) and the enable box is checked,
-We have a business DSL account,
-Our ISP says they are not blocking port 25,
-ShieldsUp reports that port 25 is open,
-Portqry reports that port 25 is filtered,
-Can’t telnet to port 25 (connect failed),
-Can’t send mail through our static IP via Thunderbird (connection timeout).
I have checked every forum I can find and every solution turns out to be something I did not overlook. If anyone can solve this on my hat’s off to you. Thanks in advance.