23

According to Google’s documentation, https://support.google.com/a/bin/answer.py?hl=en&answer=178723

It clearly says Create a TXT record containing this text: v=spf1 include:_spf.google.com ~all

Why is this not a SPF record?

RFC4408 defines SPF records, but it seems it’s not really used https://tools.ietf.org/html/rfc4408#section-3.1.1

Is that right? Should I create both TXT and SPF ?

Thanks

  • 4
    Not many domain registrars provide tools for creating and managing actual SPF records while TXT support is quite common (just for example: popular GoDaddy). That's, of course, if you are not running your own DNS server. If you can -- create both. This will also be beneficial for services that actually support SPF records (because they first check SPF and if absent -- TXT). – LazyOne Mar 28 '12 at 16:24
35

I realize this is a fairly old question, but in case anyone else stumbles upon it, here is what I found. It appears that the SPF record type is now obselete. See:

Studies have shown that RRTYPE 99 has not seen any substantial use, and in fact its existence and mechanism defined in [RFC4408] has led to some interoperability issues. Accordingly, its use is now obsolete, and new implementations are not to use it.

From: https://tools.ietf.org/html/draft-ietf-spfbis-4408bis-15#section-13.1

See also a post on cPanel's feature request forum on this topic.

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    Also RFC 7208 obsoletes 4408 and states: SPF records MUST be published as a DNS TXT (type 16) Resource Record (RR) [RFC1035] only. – Stoinov May 10 '15 at 13:16
6

Please read status of RFC4408 "Category: Experimental" and definition of this status.

Also, from RFC

It is recognized that the current practice (using a TXT record) is not optimal, but it is necessary because there are a number of DNS server and resolver implementations in common use that cannot handle the new RR type.

and, after all, SPF RR haven't any added value, compared to TXT version

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2

I would create both, since you have that ability. After you done, you can send and email to "mailtest@unlocktheinbox.com", it will auto-respond and give you a complete diagnosis of the email you sent letting you know, if you have everything set up correctly.

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1

As per satyenshah's Jul 19, 2017 reply to this post:

The dedicated type=SPF record never really caught on. Sender policies using ``type=TXT records were established too well in the early 2000's for the type=SPF record to get a foothold in the 2010's. Your authoritative DNS server probably supports publishing the SPF record, but the Internet's MX servers are satisfied querying just the TXT record.

Major services (including gmail.com and yahoo.com) only publish type=TXT record for SPF. Their administrators have figured out that the type=SPF record is unnecessary.

In most cases, there is no harm to publishing your domain's SPF policy with both record types. Two caveats:

  1. You will need to be diligent about keeping those two records manually in sync. When you update one copy of your policy record, you have to remember to update the other.
  2. Depending on your DNS server, a type=ANY query could include both TXT and SPF records in the reply, making the response larger.
    This itself has two drawbacks.
    • First, you become more susceptible to DNS amplification/reflection DDoS attacks. Second, if the size of your domain's ANY response hovers right around the 512-byte threshold between UDP/TCP,
    • Then you might run encounter a bug caused by an ambiguity in the RFC for the DNS protocol. That's rare, but it happens.

Network tools info bubble (if your entered domain shows a SPF record) sais:

More Information About Spf Record Deprecated Hostname has returned a SPF Record that has been deprecated

The use of alternative DNS RR types that was formerly supported during the experimental phase of SPF was discontinued in 2014. SPF records must now only be published as a DNS TXT (type 16) Resource Record (RR) [RFC1035]. See RFC 7208 for further detail on this change.

According to RFC 7208 Section 3.1: During the period when SPF was in development, requirements for assigning a new DNS RR type were more stringent than they are today and support for the deployment of new DNS RR types was not deployed in DNS servers and provisioning systems. The end result was that developers of SPF discovered it was easier and more practical to follow the TXT RR type for SPF.

Yet, I have also read some people report that they had trouble with email delivery until they added an SPF record.

Given that google only provides TXT records is a good indication that having a TXT entry, alone, should work.

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Considering that it is now 7 years after the RFC was published, I say that anyone still using DNS servers that can't handle unknown RRtypes is basically THEIR problem for not keeping software up to date. (Also consider that by not upgrading, how many know exploits for which they remain vulnerable). RFC 4408 said that the overloading of the TXT RRtype was a temporary measure until the IANA issued the SPF RRtype (type 99), which also happened 7 years ago.

Therefore, I say that use of the TXT RRtype for SPF purposes expired long ago. People running resolvers which check only for the TXT type are broken.

I disagree that the SPF RRtype didn't "add value." It keeps machine processible data OUT of a human readable DNS RRtype.

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  • You may like to change your mind considering Dominic's answer? – user11478 Apr 25 '14 at 15:57
  • The tone of this post is quite unfriendly and toxic. – SherylHohman Mar 24 at 18:18

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