To whitelist this on the other servers you can run the command:
apf -a 72.52.198.161
It will first need to be removed from the deny list first if it is being
blocked.
To remove the entry:
Run this command
nano /etc/apf/deny_hosts.rules
Press control w to start a search, then enter the IP 72.52.198.161. Once you find the location remove the two lines that the IP consist of, then exit and save the file with control x and then y to save and exit. After this run the command to restart the firewall:
/etc/init.d/apf restart