Firewall rules for Messenger

Hello people,

for some reasons I’m unable to send messages via Escargot (last stable release) in a domain network.
Although the connection is ok, I experience “Unable to deliver all messages to all the recipients” in the chat window, even if I’m 100% connected to the platform.
I tried to add a firewall exception for msnmsgr.exe, but without success.
I’m running the latest Escargot build, on Windows 10 1809 Enterprise.
Thank you so much in advance!

do you can’t send messages to all?

I can send messages if I’m connected via tethering to my mobile. In a domain network, I’m not able to send messages to anybody.