-----Original Message-----
From: mailop <[email protected]> On Behalf Of Boris Mutina via mailop
Sent: Monday, August 10, 2026 7:20 AM
To: [email protected]
Subject: [mailop] Greylisting practices
need advice about greylisting practices. Here's the scenario:
On 10.08.26 10:44, Scott Techlist via mailop wrote:
I use postfix as my MTA with it's after 220 checks, which effectively is
greylisting. The problem you encounter is the big guys, google, sendgrid,
etc, do have farms of servers handing their mail. So the first temp
reject from you goes to them and they properly retry later. And postfix
(or whatever greylist tool you are using) records who it rejected from. A
few minutes later the server farm retries, from a different IP this time
so it gets temp rejected again, and so on. So yes, it's a problem. I use
a tool called postallow (a newer fork of postwhite) to whitelist these
desirable senders, it basically takes the domain and scrapes their SPF
data to now all the servers they say are OK to send from. Do you get a
lot of crap in there you don't want, probably. But you still whack all
the zillion bots.
this is main reason why I gave up using greylisting a few years ago.
Luckily postfix has tool "postscreen" what is designed to detect and drop
bots, and it also support multiple dns-based lists with score weighihg.
https://www.postfix.org/POSTSCREEN_README.html
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