Message sender IP addresses go through IP reputation-based filtering. IP addresses are evaluated until the first match is found.
Messages from approved sender IP addresses bypass IP reputation-based filtering at the MTA connection level. Messages from blocked sender IP addresses are blocked.
Evaluation is done in the following order:
In the Approved IP Address list
In the Blocked IP Address list
In the Approved Country/Region list
In the Blocked Country/Region list
The Known Spam Source (KSS) in the IP Reputation settings
The Dynamic User List (DUL) in the IP Reputation settings
The Emerging Threat List (ETL) in the IP Reputation settings
An IP address added to the Approved IP Address list will not be blocked even if that IP address is also in a CIDR block listed in the Blocked IP Address list. Furthermore, that IP address will not be blocked even if it is also in the Known Spam Source standard IP reputation database list.
IP reputation-based filters use only IP address data to filter messages. You can also use sender email address and domain to filter incoming messages. Approved senders bypass IP reputation-based filtering at the MTA connection level.