Still having issues with Email in UK

I'm having intermittent email account errors when accessing my Xfinity account from my second home in the UK.  I'm using Apple Mail on a Macbook using wifi connected to the Internet.  I have full access to the internet, but when my Mail app attempts to connect to my Comcast mail server, I get the message: Online Status - Temporarily blacklisted IP address - try again later.  Some emails will come through periodically, but in general there is no email access through the wifi router. Sometime I receive email but cannot send.  I have the same issue on my mobile phone when I use a cellular connection.  

I have tried to resolve for 2 years now. Any ideas how to keep my wifi IP address from being blacklisted by Comcast?