Linux script that automatically sends an email when your WAN IP address changes, usually is default setup by your ISP. I use this to keep track of my IP in case I'm away from home and the off chance that my IP address changed, I know where home is... Take that ISP's. Setup for Ubuntu 16.04, most debian distros should work though. You may need additioinal packages, keep an eye out in your terminal.
git clone https://github.com/4n0m4l0u5/change-IP-email-me.git
nano auto_ip_check.sh
vi auto_ip_check.sh
chmod +x auto_ip_check.sh && ./auto_ip_check.sh