DKIM checker
A DKIM checker looks for a public key that receivers can use to verify mail signed as your domain.
The key lives under a selector your email provider chooses. “Not found” on common selectors does not prove a course or coaching domain has no DKIM. Enter the selector and check that name.
Nothing is stored. The check runs in your browser against public DNS. CourseSignal does not keep the domain you look up.
What a DKIM record is
DKIM publishes a public key at selector._domainkey.yourdomain. The selector is a name, not something a checker can guess for every provider. This page tries google, selector1, selector2, k1, s1, s2, default, mail and dkim, and any selector you type. A live key has a p= value. An empty p= means that name is published but has no usable key.
The checker on this page still reads SPF, DKIM, DMARC and MX together. Other free DNS tools publish the raw record. Use this one when the domain sends course or coaching email and you want the DKIM result in plain language.
How to read a fail
- Not found on the selectors we tried. This is a warning. It means those names had no key. Open a message you sent, view the original, and read s= in the DKIM-Signature header, or copy the selector from your provider. Then run the check again.
- Empty p= value. A record is there and the key is empty, which revokes that selector. If you still send with that selector, publish the current key. If you do not use it, you can leave it.
- A pass on one selector. That public key is published, so mail signed with it can be verified. Every other tool that sends as the domain needs its own DKIM too.
- This page does not send a test email. It reads DNS. It cannot tell you whether a particular campaign was signed, or whether the inbox accepted it.
Then work through the send, not only the DNS
Authentication is step one. The CourseSignal Email Deliverability Checklist walks through SPF, DKIM and DMARC, list hygiene, warm-up and a pre-send test for course and coaching email. It does not promise inbox placement.
Advert Paid download from CourseSignal.Sold and delivered by Payhip. More detail on the checklist page.
FAQ
Why does the DKIM checker say the key was not found?
It only queried the common selectors plus any selector you entered. Your provider may use a different name. “Not found” is a warning, not proof that DKIM is missing.
What is a DKIM selector?
It is the label in front of ._domainkey. Your sending tool chooses it. You can also read it from s= in the DKIM-Signature header of a message you sent.
Does a missing common selector mean I have no DKIM?
No. It means this checker did not find a key on the names it tried. Enter the selector before you treat the result as a problem.
Does a DKIM pass mean the mail will reach the inbox?
No. A pass means a public key was found for that selector. SPF, DMARC, reputation, the list and the content still decide placement.
Related: Email authentication checker · SPF checker · DMARC checker · Check if email goes to spam · Deliverability testing tools · Deliverability checklist.