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Can't connect to Exchange outside LAN

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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.

5 replies

by cg it

ok so what DNS service are you using to answer queries?

There has to be some DNS server that will answer queries of "who is" @.com and www..com etc. etc. If there isn't a DNS server that will say @.com is IP address [your public address from your ISP> inbound mail will not work.

by rsduhamel

Sorry about using the Add Comment trying to answer this, I'll figure it out yet (at least the double comment was the server's fault).

The DNS server for our domain is at the service that hosts our web site and it points to our shared IP on their network. I haven't set up an MX record to point mail to our static IP on our DSL connection yet (wise choice?). I'm trying to test the connection before changing the MX record by connecting through our static IP. I can connect to port 80 for Outlook Web Access just fine. Can't connect to port 25 by telnet or smtp. I'm using >telnet x.x.x.x 25. No joy.

by rsduhamel

The DNS server for our domain is at the service that hosts our web site and it points to our shared IP on their network. I haven't set up an MX record to point mail to our static IP on our DSL connection yet (wise choice?). I'm trying to test the connection before changing the MX record by connecting through our static IP. I can connect to port 80 for Outlook Web Access just fine. Can't connect to port 25 by telnet or smtp. I'm using >telnet x.x.x.x 25. No joy.

by vikranthp

Hi,

Did you find a solution for this problem, because i am facing the same situation and would like to know what was the solutions.

Thanks,
Vikranth

by rsduhamel

The DNS server for our domain is at the service that hosts our web site and it points to our shared IP on their network. I haven't set up an MX record to point mail to our static IP on our DSL connection yet (wise choice?). I'm trying to test the connection before changing the MX record by connecting through our static IP. I can connect to port 80 for Outlook Web Access just fine. Can't connect to port 25 by telnet or smtp. I'm using >telnet x.x.x.x 25. No joy.

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