SPF uses the deprecated ptr mechanism
URGENTWhat it means
the offending value makes receivers do slow reverse-DNS work that many of them skip entirely. The RFC tells senders not to publish it, and results are unreliable where they do.
How to fix it
Delete the offending value and authorise those servers explicitly with ip4:, ip6: or include:.
Check your own domain
This page describes the condition. To find out whether your domain has it, run the SPF test or the full checkup, which examines every record at once.
Understand it properly
This page covers one condition. For the whole picture, What is SPF, and the ten-lookup limit, or start at the Health Library.
Where this comes from
We judge this against RFC 7208 section 5.5. Every finding on this site cites the specification behind it so you can check the work rather than take our word for it.
Other SPF conditions
SPF_PTR_MECHANISM
Every fix on this site is yours to implement. If you would rather someone did it, I take this work directly.