We're getting pretty far off track here, so let's try and focus back in on the original issue.
What error message do you get from Outlook?
Did the telnet test not properly complete? Normally you should get some output similar to this:
"connected to mailserver.domain.com - Escape character is ] - we do not authorize the use of this system to transport unsolicited and or bulk email"
If that didn't happen, you couldn't connect from your machine to the server, which could indicate a firewall problem on the server, or a change on the network outside of your control.
As a test, you can run the same command with port 80 from your local workstation to see what a working connection looks like:
as port 80 is the connection to the webserver.
If your IP was blocked, you wouldn't be able to access WHM or websites.