Example Corporation uses a FortiMail unit that is operating in gateway mode, and uses greylisting to reduce the quantity of spam they receive at their protected domain, example.com.

Example Corporation wants to exempt some email from the initial greylist delay period by creating manual greylist entries (exemptions to the automatic greylisting process) that match trusted combinations of SMTP client IP addresses and recipient email addresses.

Example Corporation has a number of foreign offices. Email from these offices does not need to be greylisted.The IP addresses of email servers in the foreign offices vary, though their host names all begin with “mail” and end with “example.com”.

Rule 1 uses the recipient pattern and the reverse DNS pattern to exempt from the automatic greylisting process all email messages that are sent to recipients at example.com, and are being delivered by an email server with a host name beginning with “mail” and ending with “example.com”.

Example Corporation works closely with a partner organization, Example Org, whose email domain is example.org. Email from the example.org email servers does not need to be greylisted. The IP addresses of email servers for example.org are within the 172.20.120.0/24 subnet, and have a host name of mail.example.org.

Rule 2 uses the recipient pattern, sender IP/ netmask, and reverse DNS pattern to exempt from the automatic greylisting process all email messages that are sent to recipients at example.com by any email server whose IP address is between 172.20.120.1 and 172.20.120.255 and whose host name is mail.example.org.