Pro move: type dmarc:yourdomain.com or blacklist:1.2.3.4 straight into the box — it switches tools for you.
About this tool. DKIM puts a tamper-proof cryptographic signature on outgoing mail, published under a 'selector' in your DNS. Enter selector:yourdomain.com to check a specific selector, or just a domain and we'll probe two dozen common selectors used by the big providers.
How to read your dkim record checker results
DKIM adds a cryptographic signature to your mail. We look up the public key at selector._domainkey.yourdomain and validate it.
You need the selector to check DKIM. It is shown in the DKIM-Signature header of a message you have sent (the s= value).
A valid, correctly sized key (1024-bit minimum, 2048 preferred) is what receivers use to confirm the message was not altered.
Common problems and how to fix them
DKIM not found
Confirm you are using the right selector, and that your provider's DKIM is enabled and published in DNS. Each provider uses its own selector name.
DKIM was working, now it fails
A key rotation or a truncated DNS record can break it. Republish the full public key exactly as your provider gives it.
Common questions.What is a DKIM selector?
A label that points to a specific public key in DNS, at selector._domainkey.yourdomain. It lets you rotate keys without downtime.
How do I find my DKIM selector?
Look at the DKIM-Signature header of an email you sent. The s= value is the selector.
Does DKIM stop spoofing?
DKIM proves a message was not altered and came from an authorized key. Combined with DMARC, it stops attackers from forging your domain.