Easy setup:

yum -y install git python
cd /root
git clone https://github.com/EmpathicKernel/EmailRelayUpdate.git
mv EmailRelayUpdate/TrustIPUpdate.sh /etc/cron.hourly/TrustIPUpdate.sh
chmod +x /etc/cron.hourly/TrustIPUpdate.sh

Then edit /root/EmailRelayUpdate/settings.config with the correct domain name


This script is used for updating the trusted networks for PostFix when you are using a dynamic domain name