I have just implemented trusted forwarders. I want to know if there is
a "standard" 2822 header for the feature. So you know what I am talking
about, let me gives some details. As I described earlier,
the connection is checked against SPF for each forwarder, as in
the following simple Python implementation (inefficient for more than a
few forwarders):
for tf in trusted_forwarder:
q = spf.query(self.connectip,'',tf,receiver=receiver,strict=False)
res,code,txt = q.check()
if res == 'pass':
self.log("TRUSTED_FORWARDER:",tf)
break
else:
q = spf.query(self.connectip,canon_from,self.hello_name,
receiver=receiver,strict=False)
q.set_default_explanation(
'SPF fail: see http://openspf.com/why.html?sender=%s&ip=%s' % (q.s,q.i))
res,code,txt = q.check()
Here is an example from the log:
2005Oct30 18:57:47 [7] connect from rebelsm100.careerbuilder.com at
('66.179.14.164', 1754) EXTERNAL
2005Oct30 18:57:47 [7] hello from apply.cbdr.com
2005Oct30 18:57:48 [7] mail from <SwtsCaramel3(_at_)aol(_dot_)com>
('SIZE=84276',)
2005Oct30 18:57:48 [7] TRUSTED_FORWARDER: careerbuilder.com
2005Oct30 18:57:48 [7] Received-SPF: pass (mail.jsconnor.com: domain of
careerbuilder.com designates 66.179.14.164 as permitted sender)
client-ip=66.179.14.164; envelope-from=postmaster(_at_)careerbuilder(_dot_)com;
helo=careerbuilder.com;
2005Oct30 18:57:48 [7] rcpt to <cleom(_at_)jsconnor(_dot_)com> ()
2005Oct30 18:57:48 [7] Subject: CareerBuilder Job Application (BA003321)
2005Oct30 18:57:48 [7] X-Mailer: aspNetEmail ver 2.0.0.514
2005Oct30 18:57:48 [7] eom
Although careerbuilder.com, in addition to forging MFROM, has
no SPF record, I have a local SPF database which lists their record
for SPF checkers I administer as:
careerbuilder.com IN TXT "v=spf1 ptr ?all"
The trusted forwarder is documented via the Received-SPF header.
However, I am thinking of adding a header that is clearer as to
what has happened. For instance:
X-Trusted-Forwarder: careerbuilder.com
Is there a header in use already that I should adopt?
--
Stuart D. Gathman <stuart(_at_)bmsi(_dot_)com>
Business Management Systems Inc. Phone: 703 591-0911 Fax: 703 591-6154
"Confutatis maledictis, flamis acribus addictis" - background song for
a Microsoft sponsored "Where do you want to go from here?" commercial.
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