error unable to connect to mail server check port

error unable to connect to mail server check port

I am trying to setup the mail server settings so i can get alert email. I can ping the mail server by name or ip and verified the port is active I used the telnet test 
telnet server 25 I get mail service ready. not sure why it will not take in optmanager. I dont have to use outside mail server name or ip, internal should work, I did not see on optmanagr where to check error logs? 

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