Chapter 15 Unified Threat Management for FortiOS 5.0 : Email filter : Email filter concepts : Email filter techniques : IP address black/white list check
  
IP address black/white list check
The FortiGate unit compares the IP address of the client delivering the email to the addresses in the IP address black/white list specified in the email filter profile. If a match is found, the FortiGate unit will take the action configured for the matching black/white list entry against all delivered email.
The default setting of the smtp-spamhdrip CLI command is disable. If enabled, the FortiGate unit will check all the IP addresses in the header of SMTP email against the specified IP address black/white list. For more information, see the FortiGate CLI Reference.