# How to use Postgrey client whitelists

**URL:** <https://discourse.mailinabox.email/t/how-to-use-postgrey-client-whitelists/8355>\
**Category:** Guides\
**Created:** [August 28, 2021, 3:40pm UTC](https://discourse.mailinabox.email/t/how-to-use-postgrey-client-whitelists/8355 "2021-08-28T15:40:12Z")\
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**Author:** ![openletter](https://discourse.mailinabox.email/letter_avatar_proxy/v4/letter/o/f1d935/32.png) [@openletter](https://discourse.mailinabox.email/u/openletter)\
**Post date:** [September 22, 2021, 1:49pm UTC](https://discourse.mailinabox.email/t/how-to-use-postgrey-client-whitelists/8355/5 "2021-09-22T13:49:23Z")

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Sure, but you could just say that about everything and not use greylisting. The purpose of the filter is to weed out non-RFC compliant mail servers. One goal of my tutorial here is to maintain this functionality to the extent possible.

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