As per satyenshah's Jul 19, 2017 reply to this post:
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:
- 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.
- Depending on your DNS server, a
type=ANY query could include both
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.