Re[2]: [Exim] Callout verification

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Author: Philip Hazel
Date:  
To: Andy Fletcher
CC: exim-users
Subject: Re[2]: [Exim] Callout verification
On Fri, 7 May 2004, Andy Fletcher wrote:

> My knowledge of exim may show as thin here, but don't forwarded
> addresses get verified with recipient verification - if someone sets
> and alias to forward elsewhere, then the destination address is
> checked?


Only by trying to deliver the message to it. :-) There is no point in
pre-verififying. (You are probably thinking of errors_address, but that
is verified without callout.)

> I'm still not sold on why "use_sender" is a good idea on recipient
> callouts, but not sender.


It it only a good idea if the hosts to which you make the callout alter
their behaviour depending on the sender (e.g. sender A is permitted to
mail to recipient B, but sender C is not). Otherwise, it just wastes
resources because the caching is not so effective.

Typically, internal hosts to which you do recipient callouts will trust
the gateway host, so will not themselves be doing sender callout checks.

--
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