Is there some sort of trick to this? I tried "smtp-relay.gmail.com" with port 25 and 587 and I get the "cannot connect to the SMTP server". I also tried it with the IP address and I was able to ping "smtp-relay.gmail.com" from the CentOS server.
Hi Clayton, did you enter all the information, including user name and password? When you try to add the SMTP server, the system will actually confirm that it is able to connect to the server before accepting the credentials.