Re: [exim] Configuration variable to *not* remove duplicates…

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Author: Philip Hazel
Date:  
To: Laurent Fousse
CC: exim-users
Subject: Re: [exim] Configuration variable to *not* remove duplicates.
On Sat, 5 Aug 2006, Laurent Fousse wrote:

> I have:
>
>     testexim1: laurent
>     testexim2: laurent

>
> in my /etc/aliases file. If I send an email to both
> testexim1@??? and testexim2@??? from
> another host, I see from the procmail log that:
>
>     - procmail is run once,
>     - the RECIPIENT variable is set to laurent@???
>       which is the local recipient after alias expansion is done. The
>       actuel recipients are stored in the Envelope-To header,
>     - the exim log file shows only a delivery to one recipient:


This is entirely as documented (grep spec.txt for "duplicate" - it's all
there). Exim does not do duplicate deliveries except to pipes that have
*different* immediate parents. You would get two deliveries for:

testexim1: |/some/pipe
testexim2: |/some/pipe

There are several reasons for not doing duplicate deliveries to
mailboxes. One is the idea that mostly, people don't want them. Consider
cases like:

postmaster: joe
hostmaster: joe

and messages sent to both postmaster & hostmaster. The other
consideration is handling errors. The current implementation just
remembers that it has delivered to such and such a mailbox. It would
have to remember how many times it had done so, and, in the case of
address redirection, which particular copy it had or had not delivered.
And if one copy succeeds and one fails, do you send a bounce message or
not? I didn't want to have to think that one out.



-- 
Philip Hazel            University of Cambridge Computing Service
Get the Exim 4 book:    http://www.uit.co.uk/exim-book