Bright House Networks - Legacy → [Internet] sudden smtp-server rejection

for the last several years, I have used smtp-server.cfl.rr.com as my outbound server for all my email accounts within outlook and thunderbird. This morning, I received a message "An error occurred while sending mail. The mail server responded: 4.1.8 - Domain of sender address bxxx@xxxxxxxxx.com does not accept inbound mail [R0307001]. Please verify that your email address is correct in your Mail preferences and try again."

Has something change on rr enforcement side in the last 24 hours?

I changed the outbound to my hosting email servers and everything is delivered.

I am just wondering about the change....
and why after nearly 10 years is this in effect

That's not us...that's your recipients server that is doing that.

Check with the recipient. We have issues like that at our work and its usually the receivers spam or firewall that only allows certain addresses or sets of IP addresses.