Mailing List Archive

> -----Original Message-----
> From: owner-srs-discuss@v2.listbox.com
> [mailto:owner-srs-discuss@v2.listbox.com] On Behalf Of Stuart
> D. Gathman
> Sent: maandag 22 november 2004 6:06
> To: srs-discuss@v2.listbox.com
> Subject: RE: Re[2]: [srs-discuss] Help - How to unwind an SRS address?
>
> On Sun, 21 Nov 2004, Mark wrote:
>
> > Yes. The problem is, of course, programs like SA, who like to have a
> > go at SPF too. With no SRS 'original' Return-Path to be found any
> > more, they are stuck (I'm sure something can be done with HELO,
> > in those cases; but that offers no real substitute for per-virtual
> > domain SPF policies).
>
> SPF is performed on the SRS address. That is the whole point of SRS.
> The only possible reason to unwind SRS or SES is because you want to
> compare the original MAIL FROM with some rfc2822 header, or at least
> display it to the end user (although if the user is knowlegeable enough
> for the information to be useful, they should really see the full
> SRS/SRS whatever MAIL FROM).

Exactly. :) That was my point precisely; if you 'unwind' the SRS address
before writing the Return-Path, an LDA like procmail, or processing agent
like SA, can no longer do the SPF check on the SRS address. Best,
therefore, to leave the SRS address exposed to the recipient in at least
the Return-Path.

- Mark

System Administrator Asarian-host.org

---
"If you were supposed to understand it,
we wouldn't call it code." - FedEx

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On Sat, 20 Nov 2004, Chris Drake wrote:

> Hi,
>
> Please can someone give me a regex or *simple* instructions on how to
> reconstruct the real senders email address from an SRS one (pref
> without installing anything)?

I haven't checked this. And I did put a few extra (?:) constructs in to
clarify the blocks. I used [^=]+ to match each section.

s/^SRS0[-+=](?:[^=]+)=(?:[^=]+)=([^=]+)=([^@]+)@/$2@$1/
HH0 T0 domain user
s/^SRS1[-+=](?:[^=]+)=(?:[^=]+)=(?:[^=]+)=[-+=](?:[^=]+)=(?:[^=]+)=([^=]+)=([^@]+)@/$2@$1/
HH1 T1 fwdomain

SRS addresses are those matching ^SRS[01][-+=] as noted by Mark.

S.

--
Shevek http://www.anarres.org/
Robust Sender Policy Framework (SPF) http://www.libspf2.org/
SRS for the next generation http://www.libsrs2.org/

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