"Can't connect" is a too-vague error message, not giving you much to go on. For example, it's unclear if it really means no connection, or just that the maybe-connected-to server didn't reply.
From a system that can't connect, can you ping or tracert to the SMTP server? That's to say, in a terminal window, issue
>ping servername
and also try
>tracert servername
and see if they seem to work. There might be a routeing problem between your machine and the server, and that's not necessarily caused by anyone purposefully blocking traffic.
I googled for: outlook 0x80042109 and found this discussion (which I only skim read a small amount of) which suggests you might be trying to connect to the wrong port, eg:
"I have figured out the problem, the SMTP port number that Outlook sets as the default was not working
for some reason. Outlook sets the outgoing port number as 25, and my mail provider said to use the
other default, ports 587."
https://answers.microsoft.com/en-us/...e-c49e6864509c
I think you also need to ask your company IT people why they seem to be blocking Telnet traffic; telnet is really useful for testing connections.