Re: [exim] respecting duplicate deliveries to pipes

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Author: Philip Hazel
Date:  
To: Ollie Cook
CC: exim-users
Subject: Re: [exim] respecting duplicate deliveries to pipes
On Tue, 9 Nov 2004, Ollie Cook wrote:

> The behaviour I'm seeing, as shown in the debugging output is that as the
> second (and subsequent) addresses are routed to a previous address they
> are discarded:
>
>    postmaster@??? is a duplicate address: discarded

>
> This happens at line 5095 of deliver.c.


1. This is entirely as designed. I never thought people would *want*
duplicate deliveries. :-)

2. Note that if you ask Exim to add an Envelope-To: header, it will
include all the original addresses that routed to the one delivery.

> Unless anyone has any better ideas, I'll try to provide Philip a patch to make
> the de-duplication at line deliver.c:5095 conditional (probably per
> configurable per transport) and hope he might include it in future releases.


3. It's not as easy as that. If you ask Exim to deliver twice to the same
address and only one delivery succeeds, it has to remember that. At
present, it just remembers that it has or has not delivered to that
address. A way would have to be found to identify each duplicate address
differently so that it could remember which one had been delivered and
which one had not. This is not trivial. There are no doubt other places
where the address is used as an identification "tag" of some sort. We
are talking of some deep re-design here. Consequently, I am not
enthusiastic.

> If anyone does have a better idea on how to solve this problem, though, I'd be
> glad to hear it!


Does the Envelope-To: information I've given above help?

-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.
Get the Exim 4 book:    http://www.uit.co.uk/exim-book