Re: [exim] Sender rate limiting based on recipient address?

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Author: David Woodhouse
Date:  
To: Osborne, Paul (paul.osborne@canterbury.ac.uk), Patrick von der Hagen, exim-users@exim.org
Subject: Re: [exim] Sender rate limiting based on recipient address?
On Tue, 2015-10-20 at 07:51 +0000, Osborne, Paul
(paul.osborne@???) wrote:
>
> So when google generates the MDF it goes to mxout (as part of the
> SMTP transaction) - which then sends it round to mxin and so back to
> the beginning of the pipeline.  It is all made worse by our addresses
> in O365 actually being something like:  paul27@???
>  - so by the time the address has been rewritten any sense of the
> original inbound mail and any MDF due to the forwarding issue is a
> right pain to correlate.


I must be missing something here. The important part of a bounce
messages is not the destination, but the *sender*. Which must always be
empty — MAIL FROM:<>.

Such messages can never trigger a mail loop, because they must *never*
trigger any kind of autoreply.

So even if your user were to send *himself* a message, it should
generate a bounce. That bounce is undeliverable too, but that *doesn't*
in turn produce another one.

This is the very basic principle of how bounces work; if you are
violating this somehow, then you need to fix *that*, not play with
rate-limiting.

--
dwmw2