No DKIM key found at the usual selectors
NOTEWhat it means
We probed N selectors that Google, Microsoft, Zoho, Mailchimp and the other common providers use, and none of them answered for example.com. That means either nothing signs your mail, or it signs with a selector only you know.
How to fix it
Look at the DKIM-Signature header of a message you sent, the s= value is your selector, and check it directly. If there is no such header, enable DKIM signing in your mail provider.
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 3.6.2.1. 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_SELECTOR_NOT_FOUND
Every fix on this site is yours to implement. If you would rather someone did it, I take this work directly.