In some cases, you may want to manually configure some greylist entries. Manual greylist entries are exempt from the automatic greylisting process, and are therefore not subject to the greylist delay period and confirmation.

For example, a manual greylist entry can be useful when email messages are sent from an email server farm whose network is larger than /24. For very large email server farms, if a different email server attempts the delivery retry each time, the greylist scanner could perceive each retry as a first attempt, and automatic greylist entries could expire before the same email server retries delivery of the same email. To prevent this problem, you can manually create an exemption using common elements of the host names of the email servers.

For more information on creating manual greylist entries, see “Manually exempting senders from greylisting”.