Isn't it just easier to always do the SRS rewrite, rather then having to
do a DNS query, wait for the response, check the result...?
Please respond to exim-users@???
Sent by: exim-users-bounces@???
To: John Horne <john.horne@???>, exim-users@???
cc: (bcc: Dan Mitton/YD/RWDOE)
Subject: Re: [exim] SRS forward
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User Filed as: Excl/AdminMgmt-14-4/QA:N/A
On 2010-06-30 at 15:31 -0700, Phil Pennock wrote:
> On 2010-06-30 at 23:03 +0100, John Horne wrote:
> > On Wed, 2010-06-30 at 14:18 -0700, Phil Pennock wrote:
> > > On 2010-06-30 at 20:15 +0000, Christian Gregoire wrote:
> > > > I've written an SRS forward router, which works fine but it always
rewrites the sender address when I'd expect the rewrite to occur only if
the incoming domain has an SPF record. Is that possible ?
> > >
> > > condition = ${if match{${lookup
dnsdb{defer_never,txt=$sender_address_domain}}}{\N^v=spf1\s\N}}
> > >
> > We have found that occasionally multiple TXT records are present (for
> > other things than SPF), and so tend to use a multiline regex. In the
> > above example it would become:
> >
> > ...{\N^(?m)v=spf1\s\N}}
>
> Good catch, thanks. In addition ...
Actually, you need to have the (?m) come *before* the ^ because it
changes the meaning of the caret.
> Prior to Exim 4.70, the TXT behaviour of dnsdb was problematic. 4.70
> and 4.71 have behaviour geared towards DKIM.
>
> As of Exim 4.72, this is now tunable. To get the interpretation defined
> by RFC 4408, where individual text strings within an RR are concat'd
> together, but keep newline termination between strings, you want:
>
> ${lookup dnsdb{>\n; txt=$sender_address_domain}}
At the { exim -be } prompt:
> ${if match{${lookup dnsdb{>\n;
defer_never,txt=spftest1.test.globnix.net}}}{\N(?m)^v=spf1\s\N}
{Yup}{Nope}}
Yup
> ${if match{${lookup dnsdb{>\n;
defer_never,txt=spftest2.test.globnix.net}}}{\N(?m)^v=spf1\s\N}
{Yup}{Nope}}
Yup
> ${if match{${lookup dnsdb{>\n;
defer_never,txt=spftest3.test.globnix.net}}}{\N(?m)^v=spf1\s\N}
{Yup}{Nope}}
Yup
Note that "spftest1" includes non-SPF TXT records and the 2,3 variants
instead just break the RR up into multiple strings. All publish both
TXT and SPF record types, but Exim only supports TXT at this time.
-Phil
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