Re: [exim] How to avoid generating backscatter?

Richard.Hall wrote:
> Hello, hope someone can help with this hypothetical (at the moment)
> situation ...
>
> - spammer sends email to userA@domainA
> - domainA fails to detect that it is spam
> - userA has set up forwarding to userB@domainB
> - domainA attempts to forward email to userB@domainB
> - domainB detects that it is spam, and rejects it (5xx)
> - domainA sees 5xx, generates NDR, attempts to send it to ... oops,
> you guessed, forged sender.
>
> Is there any way for domainA to prevent the generation, or at least
> the transmission, of the NDR? (Other than improving its spam
> detection rates!!)
>
> For bonus points, can domainA hang on to the original email and/or
> the NDR (eg by freezing it/them), for later inspection?
>
> Marks will be deducted for mentioning SPF ;-)
>
> TIA,
> Richard Hall

Assuming you know (or can find out) the forwarding address at SMTP time,
you could do a recipient verification call-out. Might get contentious if
you're going to be doing a lot of it though (see the various discussions
on sender verification call-outs which I hope we won't re-hash again...)

Regards

Richard

--
Richard Rogers
IT Development and Innovation Manager
Staffordshire University


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