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List:       postfix-users
Subject:    Re: Preferred/maintained greylisting options?
From:       Vincent Pelletier <plr.vincent () gmail ! com>
Date:       2020-05-25 1:59:08
Message-ID: CAF78GY0P6_obgApjQXw5O2ni-mVWY-3RRPazkVV-+NtiEq5UhQ () mail ! gmail ! com
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On Fri, May 22, 2020 at 5:43 AM Ralph Seichter <abbot@monksofcool.net> wrote:
> Yeah, delays... Used to be people understood the difference between
> asynchronous messaging (i.e. email) and instant messaging. Nowadays it
> seems that no day goes by without somehing along these lines:
>
>   "Hi. We have not seen you login using this browser, this IP address or
>   during this week. Therefore we have just sent you an email containing
>   a verification code, which will remain valid for 10 minutes."

Personally, I've hacked together a mixed SPF check + greylist milter.
If SPF check passes, the greylist is skipped, and any other result
("do not reject any mail" approach modulo greylisting) goes to greylist.
The companies which send such emails are likely (in my experience)
to have a properly setup SPF, so this solved these issues for me.

I'm not planning on releasing the source, it's really an ugly milter, but
I'm putting the idea out here - and maybe I'll learn it has already been
done and properly implemented...

Regards,
-- 
Vincent Pelletier
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