Greylisting - how?

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bostjanc
Posts: 165
Joined: 01 Jun 2016 17:18

Greylisting - how?

Post by bostjanc »

Hi there.
when we open efa web console: https://efa/mailscanner/grey.php
and see there is a message greylisted we mark that message and select option: Move selected entries to whitelist
But that does not enforce message to come to users mailbox.
There is still greylisting period of time to wait to unblock those messages.
shouldn't that selection and chosing "Move selected entries to whitelist " deliver message immediately?

with best regards
B
Odon Garma
Posts: 33
Joined: 08 May 2017 14:10

Re: Greylisting - how?

Post by Odon Garma »

if a message is greylisted, the sender MUST resend the message. after which time the sender does resending may vary.

if you move an E-Mail to your whitelist, the next attempt to deliver e-mail will not be greylisted.

to make it clear: no e-mails are stored on efa will sender ist grey.

https://en.wikipedia.org/wiki/Greylisting

Greetz
budy
Posts: 74
Joined: 10 Sep 2017 07:33

Re: Greylisting - how?

Post by budy »

When a message gets greylisted, postfix actually does not accept it, but returns a temporary 4xx error instead. The sending mta will see that and will retry sending that message at a later time. This had been originally implemented in the era where massive amounts of SPAM had been send out by hosts via modems (yes!!) and where the sending agents were too dump to implement the full smtp stack. Since greylisted messaged are initially not accepted by postfis they cannot be released…

This use of greylisting has somewhat diminished over the course of the last decade, but it still is a useful tool to use at almost no cost. Whitelisting on the other hand will have postfix accept all future messages from that sender/domain.

Cheers,
budy
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