On 2018-11-18, Aki Kyo via Exim-users <exim-users@???> wrote:
> Hi, I have a question about handling messages with multiple recipients in Exim.
>
> I want to run something like rspamd and apply per-user spam filtering,
> which means multiple recipients might have different spam scoring
> results or different white/black list results on the same message. I
> know it depends when it's done, like during the SMTP process or after
> accept.
>
> I use Postfix now and I can force it to reply with 452 4.5.3 error
> ("too many recipients") if there are 2 or more recipients so rspamd
> milter will never have multiple recipient messages but this is bad
> behavior and frowned upon I believe.
> How does Exim handle this situation, what is the recommended approach
> taken by Exim administrators? I appreciate links, opinions, tips.
> Thank you.
Ideally you use PRDR if the source requests it.
PRDR:
https://tools.ietf.org/html/draft-hall-prdr-00
https://www.exim.org/exim-html-current/doc/html/spec_html/ch-access_control_lists.html#SECTPRDRACL
I don't know how to get exim to scan per recipient though - mainly
because I have not looked.
If PRDR is not used then you have to choose between potentially
generating backscatter or limiting the source to one RCPT per MAIL
There's many things you can base that decision on SPF would be one a
softfail "~" seems enough to justify a defer response for the extra rcpts.
--
When I tried casting out nines I made a hash of it.
