[Pkg-exim4-users] Multihomed smarthost

ael law_ence.dev at ntlworld.com
Wed Dec 25 09:53:20 UTC 2013

On Wed, Dec 25, 2013 at 01:18:31AM +0100, Hans Ekbrand wrote:
> On Mon, Dec 23, 2013 at 10:06:54AM +0000, ael wrote:
> > My smarthost is multihomed: dns lookup replies with a list of addresses
> > none of which matches the "collective address".
> > 
> > So looking up smpt.example.com yields
> >  x.y.z.4
> >  x.y.z.5
> >  x.y.z.6  etc.
> > 
> > Reverse dns on these addresses gives smtp1.example.com,smtp2.example.com
> > and so on.  This is a very common way of spreading load and adding
> > resilience, I think.
> > 
> > However, setting
> > dc_smarthost='smtp.example.com::578'
> >  in update-exim.conf.conf
> > fails the reverse dns test - which is perhaps not very surprising. 
> I thought the point with a reverse dns test was used to make it harder
> for spammers to mail to you, not to stop you from sending mail with
> whatever smarthost you want to. Are you asking how to make exim stop
> using that test?

Well, the current implementation prevents me from using the smtp pool's
address. What I would like is to have a smarter reverse dns test that
can cope with multiple ip pointers returned. But I can't think of
a very simple way of doing that: perhaps an re looking for a match
on the "tail" of the domain in such cases?

It seems to be something to do with the Debian template because when I
tried a very simple configuration without a reverse dns test, it worked
fine. But that was several years ago, and I forget the exact details.


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