DKIM record checker
Enter a domain to find its DKIM public keys and see whether they are valid and strong enough for Gmail, Outlook and Yahoo. Add the selector if you know it.
No selector? Leave it empty and we try the common ones (google, selector1, k1, s1…).
Checking a whole list?
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How it works
What DKIM does
Your mail service signs every message with a private key. Receivers fetch the matching public key from your DNS to check that the message really comes from your domain and was not changed on the way.
Selectors
Each service publishes its key under its own name, the selector, at selector._domainkey.yourdomain. Without a selector, we try about 30 common ones, such as google (Google Workspace), selector1 (Microsoft 365) and k1 (Mailchimp).
What we check
That the record holds a valid DKIM key, its type and length (2048-bit RSA is the recommended size), and settings that weaken it: a revoked key, test mode, or SHA-1 only.
Questions
Where do I find my DKIM selector?
Open an email sent from the domain, show the original message (its headers) and find the DKIM-Signature line: s= is the selector and d= the signing domain. The DKIM page of your mail service shows it too.
Is a 1024-bit DKIM key still OK?
It still works, but 2048-bit keys are recommended. Most services let you create a new 2048-bit key under a new selector, so you can switch without any interruption.
Why does the checker find no DKIM record?
Either the domain does not sign its mail with DKIM, or it uses a selector that is not on our list. Find the selector in a message header (s= in DKIM-Signature) and check it directly.
Do I need DKIM if I already have SPF?
Yes. Gmail and Yahoo require both from bulk senders, and DKIM still passes when a message is forwarded, where SPF often fails. DMARC then passes when either one passes for your domain.
Related guides
- What Is a DKIM Record? How to Find Your Selector, Check Your Key and Fix DKIMWhat a DKIM record is, how to find your DKIM selector, what a good key looks like (2048-bit RSA), and how to fix the most common DKIM problems.
- Gmail, Yahoo and Outlook Sender Requirements in 2026: The Complete ChecklistWhat Gmail, Yahoo and Microsoft Outlook require from email senders in 2026: SPF, DKIM, DMARC, spam rate limits and one-click unsubscribe, with a setup checklist.
- Why Do Verified Emails Still Bounce? 7 Reasons and What to DoYou verified your list and some emails still bounced. Here are the seven usual reasons, how to tell them apart from the bounce code, and how to prevent each one.