DKIM key at {selector} has been revoked
CODE REDWhat it means
The record at selector1._domainkey.example.com has an empty p= value, which formally revokes the key. Every signature made with it fails, so signed mail is treated as unsigned.
How to fix it
Publish the current public key in the p= tag, or remove the record entirely if the selector is retired.
Check your own domain
This page describes the condition. To find out whether your domain has it, run the DKIM 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 DKIM, selectors and key strength, or start at the Health Library.
Where this comes from
We judge this against RFC 6376 section 3.6.1. Every finding on this site cites the specification behind it so you can check the work rather than take our word for it.
Other DKIM conditions
DKIM_KEY_REVOKED
Every fix on this site is yours to implement. If you would rather someone did it, I take this work directly.