We are using windows 2003 to configure SMTP server. In our existing environment we want to configure a SMTP server which will allow relay to authenticated domain users from internet only. SMTP server is inside the PIX firewall and we have statically mapped with a Public IP. We have opened the port 25 for this public IP from outside.
When I use private IP of the SMTP server to send and receive mail it works smoothly but when I try to connect with the Public IP it say’s “Unable to relay” and “authentication fails”.
The configuration which I have done in the SMTP server i.e. simply I have installed SMTP service and Default SMTP virtual Server>Properties>Access>Select basic authentication with the default domain name.
And Delivery>advanced>fully qualified domain name>smtp2.domainname.com (here smtp2.domain name is register in the ISP with A record)
And SMART Host>points to Front end server (in the front end server I have enable relay for the new SMTP server with its local IP address.)
How authentication goes on for this SMTP service.
Do I have to open any other port other than 25? And what configuration that I am missing in my new SMTP server; for that it is not accepting any request from Internet.