Re: [spfbis] SPDF Domain Name Syntax

Mark Andrews <marka@isc.org> Tue, 03 May 2016 02:39 UTC

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To: Tobias Perschon <tobias@perschon.at>
From: Mark Andrews <marka@isc.org>
References: <AM4PR09MB065930FACFA477EA02EE919ADD790@AM4PR09MB0659.eurprd09.prod.outlook.com>
In-reply-to: Your message of "Mon, 02 May 2016 18:55:37 +0000." <AM4PR09MB065930FACFA477EA02EE919ADD790@AM4PR09MB0659.eurprd09.prod.outlook.com>
Date: Tue, 03 May 2016 12:39:38 +1000
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Subject: Re: [spfbis] SPDF Domain Name Syntax
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In message <AM4PR09MB065930FACFA477EA02EE919ADD790@AM4PR09MB0659.eurprd09.prod.outlook.com>;, Tobias Perschon writes:
> Dear Sir or Madam,
>
> I have a question regarding RFC 7208. Is a domain name e.g. for an "a:"
> directive supposed to be a FQDN; more precisely: can a domain name
> contain a trailing dot?
> e.g.: should this be able to be handled by any software that implements
> spf:
> v=spf1 a:domain.com. ~all
>
> Postfix for example has no problems with an domain name with trailing dot
> but I have found a software "mdeamon" which cannot perform a dns lookup
> if the domain name is a FQDN (with trailing dot). I wrote the developers
> but they say, they think it's not a bug in their software because "all of
> the pages about SPF, don't talk about domains with trailing dot" and the
> RFC does not make it explicit if a FQDN is acceptable.

Postfix is being liberal in what it accepts.  It should already be
treating names in SPF records as absolute (like all names in DNS
records).

Appending periods is a local convention to prevent suffixes being
appended be they search lists or current origin in master files (
which doesn't apply the the contents of TXT (SPF) records).

Mark

> I hope you can clarify.
>
> Kind regards,
> --
> Tobias Perschon
> Bitconnect EDV/IT Dienstleistungen & Handel e.U.
> --
> https://www.bitconnect.at
> tp@bitconnect.at<mailto:tp@bitconnect.at>
> +43 (0) 699 10 86 75 17
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka@isc.org