Can you ping smtp.office365.com from the same workstation?

I'd be tempted to believe the error message; the ping test will confirm if it fails. Maybe the DNS server or something else local is blocking it.

Without a relay server, I try to avoid directly connecting in cases where the message recipients will be beyond the client's domain.

Both google and microsoft discourage this connection type (as adagio doesn't support Oauth):

https://techcommunity.microsoft.com/blog...tp-auth/4114750
https://support.google.com/a/answer/14114704?sjid=3689632868214876468-NA