Re: [exim] Using the SRS support in Exim 4.50+

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Autor: Chris Webb
Datum:  
To: David Woodhouse
CC: exim-users
Betreff: Re: [exim] Using the SRS support in Exim 4.50+
David Woodhouse <dwmw2@???> writes:

> http://www.infradead.org/rpr.html will do it, btw.


Gosh, you've implemented SRS-style rewriting entirely in Exim string
expansion! Does this have any advantages over the libsrs_alt support now
integrated into Exim 4.50 as part of the exiscan-acl patch? It's certainly
a very impressive of the power of the string expansion system!

> You don't have to do it unconditionally. You could do it only for mail
> which originates from SPF-afflicted domains, and which is also destined
> to servers which you know are rejecting mail for an SPF failure.


As you say, the former ought to be relatively straightforward to test,
although I'd like to be able to be more specific than just testing for an
SPF-affected domain. There may be SPF domains that allow a (perhaps very
wide) subset of hosts including our machines (especially people we've
complained to in the past, who've just added our mail servers to their SPF
host list!), and we don't want to rewrite for that case if we can help it.
The SPF checking code is already in Exim 4.50 for the spf ACL condition,
it's just getting at it and applying it to the MAIL FROM address from within
a router condition that's the tricky bit!

(I'd like to avoid the extra admin work of having to maintain a list of
hosts that reject on SPF mismatch, so I'm inclined just to never generate
mail that could provoke such a failure, despite this going somewhat against
the grain.)

Cheers,

Chris.