I have a vendor email rejected from coming into my exchange server. it gives me this error. my certificate on my exchange server expires in 2020. so my certificate is fine. i attached the error the vendors sees as it bounces back. and i attached a screen shot of my receive connector. this error stood out.
"Remote Server returned '<[X.X.X.X] #4.7.0 SMTP; 403 4.7.0 authentication failed>'"