Just received a Delivery Incomplete on a message I sent to a project forum thread. The error message is:
The recipient server did not accept our requests to connect. Learn more at https://support.google.com/mail/answer/7720[apps.magicjudges.org 35.167.61.175: generic::failed_precondition: connect error (111): Connection refused]
I’m sending via Gmail web interface. Let me know if you need message headers.