Email sending down because client settings must be changed
Site:
I had the same problem with send as others have. I fixed it by changing my email client's settings to no longer use Port 25. See this web page for instructions:
https://customer.comcast.com/help-and-support/internet/email-client-programs-with-xfinity-email
It seems they're blocking port 25 gradually so they don't have every customer call tech support at the same time.