[Mimedefang] Delaying 2xx as long as possible with stream_by_xyz()

[Steffen Kaiser]

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On Tue, 31 Jan 2017, Steffen Kaiser wrote:
> On Mon, 30 Jan 2017, Kevin A. McGrail wrote:
>
>> I think I need to play with this more.  Then I can more definitely say what 
>> happens under xyz cases.
>
> I'm pretty sure there had been suggestions like this - probably without
> stream_by_*() because of the flag Dianne mentioned - in the past. However
> I cannot find it in my archive, maybe this one:
>
> http://mimedefang.roaringpenguin.narkive.com/IYvAt216/spam-with-more-than-one-recipient-reject-or-not
>
> a thread  "Spam with more than one recipient - reject or not?"
> Michal Jankowski 2005-08-16 08:45:53 UTC
>
> there had been more, I guess.

some wild idea:

you could resend the message manually and collect all processings into a 
database; while the state of the resent messages is not satisfying hold 
the SMTP link open; if the client breaks the connect and retries, hold
the connection. (DATA phase)
Use some hash / ID derived from the message in order to identify it later, 
even if comes from different IPs and different HELOs.
Record IP and HELO as well.

If a message arrives in RCPT TO phase with a 2nd recipient, check if there 
is "pending" "held" message from this IP (range) and HELO and with both 
recipients.
Now, do someting "cunning", because it might be possible that there 
are two or messages from that IP with more than one recipient.

;-)

Either tempfail all-but-one, tempfail according that recorded status' and 
check if the message is the same. ...

- -- 
Steffen Kaiser
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