IP Address Blocked by Email Server

Xfinity email has not synced on my mobile phone since early Sunday morning (had a similar issue about a week ago).  Have attempted deleting comcast email account and adding back but always get the same message "Couldn't Verify Account. Your IP address has been blocked by the email server. Contact your email service provider for help." I have changed passwords and tried restarting the phone multiple times.  When is the issue going to be fixed???