Policy Patrol can make use of greylisting, a method that can block spam and virus emails sent by spammers and infected zombie machines. Greylisting initially rejects emails from new (non white-listed) senders for one minute. Legitimate emails will still get through, but spam and virus messages will not. This is because unlike spam engines and zombie machines, regular mail servers resend their messages upon initial rejection.
Last Review: 2016-01-26 19:40:57 UTC
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