No port 25 flow. Port not open.
Posted on 2012-12-31
I have a functional exchange 2003 server - all works fine but I need to make a change to have the mail.mycompany.com resolve to another ip address - on another router - which is a draytek 2820. This is on a separate phone line.
Before I change the ip address that the mail server url points to, I wanted to verify the flow of port 25 traffic through the router - so that when the change takes place, it should be a fairly seamless cut over -and the mail flows to another ipaddress/router and then to the mail server.
So I have duplicated the port settings on the 2820 and tried to telnet to the external ip on 25 - but no connection -it wont let me. Even with both port forwarding and open port set (just to see what happens) its still bounces back. Port scans show the port is not open. Management interface shows ports defined as default but none mention 25. The ISP is the same as the other line that works ok - doesnt hesitate on telnet to 25. Cant think right now what I'm doing wrong - probably something so obvious I cant see it.. any pointers? Thanks