Re: [ietf-smtp] [Emailcore] Proposed ESMTP keyword RCPTLIMIT

Tony Finch <dot@dotat.at> Tue, 20 April 2021 20:09 UTC

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Date: Tue, 20 Apr 2021 21:09:00 +0100
From: Tony Finch <dot@dotat.at>
To: Ned Freed <ned.freed@mrochek.com>
cc: John R Levine <johnl@taugh.com>, ietf-smtp@ietf.org
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References: <cone.1615844513.220592.51342.1004@monster.email-scan.com> <20210315234648.563C0708B340@ary.qy> <CAO=DXp-+fJwsNegzu3zgwDLtCcSF104AUF=i+_GMgSYVBAKjWg@mail.gmail.com> <01RY24IJ225Q0085YQ@mauve.mrochek.com> <4fe09f20-66ee-b3c-94bb-be654b8354bc@taugh.com> <01RY292U84V40085YQ@mauve.mrochek.com>
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Subject: Re: [ietf-smtp] [Emailcore] Proposed ESMTP keyword RCPTLIMIT
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Ned Freed <ned.freed@mrochek.com> wrote:
>
> I assume the Exim and Postfix limits are per-host, which in most cases
> translates to per-IP.

Exim can rate-limit per almost anything, because the lookup key for the
measured rate is an arbitrary string expansion. (typically it will be
the client's IP address or authenticated username)

It also has options for counting the rate of connections, or messages, or
recipients.

Some of this flexibility was because I didn't know what policies would
work in practise, and it did take a fair amount of experimentation to get
something that was not too disruptive. (I cared about catching outbound
spam, typically from compromised accounts.)

Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>  https://dotat.at/
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