blacklisted IP

Hello, I see others have had this problem.  All of my @comcast.com e-mail accounts are now receiving the error message "Temporarily blacklisted IP address - Try again later".  I'm using Apple's Mail.  This is happening across all of my devices.  I've opened a case, but have not heard back.  What should I do to resolve this problem?  I tried getting an update today by calling Xfinity, but the call was lost after holding for 55 minutes.  Any help would be appreciated.

  I did notice that one post dealt with being out of the US.  I too am out of the US.

Thank you,  RRM