esc

DKIM Checker

Look up a DKIM selector, validate the DKIM DNS TXT record, inspect the public key and check key type, strength and revocation status.

._domainkey.
Examples 20230601 · google.com selector1 · outlook.com k1 · mailchimp.com
DKIM Record Valid TXT RSA · 2048-bit
selector1._domainkey.outlook.com
Published as a DNS TXT record · selector selector1 · 437 characters
v=DKIM1;k=rsa;p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAvWyktrIL8DO/+UGvMbv7cPd/Xogpbs7pgVw8y9ldO6AAMmg8+ijENl/c7Fb1MfKM7uG3LMwAr0dVVKyM+mbkoX2k5L7lsROQr0Z9gGSpu7xrnZOa58+/pIhd2Xk/DFPpa5+TKbWodbsSZPRN8z0RY5x59jdzSclXlEyN9mEZdmOiKTsOP6A7vQxfSya9jg5N81dfNNvP7HnWejMMsKyIMrXptxOhIBuEYH67JDe98QgX14oHvGM2Uz53if/SW8MF09rYh9sp4ZsaWLIg6T343JzlbtrsGRGCDJ9JPpxRWZimtz+Up/BlKzT6sCCrBihb/Bi3pZiEBB4Ui/vruL5RCQIDAQAB;n=2048,1452627113,1468351913
Key type
RSA
Key size
2048-bit
Hash
SHA-256
Strength
SHA256:Ed31w4TjV+ RSA-2048
Validation
7 passed
DKIM record found at selector selector1
A TXT record exists at selector1._domainkey.outlook.com.
Pass
Starts with the v=DKIM1 version tag
The record opens with the correct, case-insensitive version token.
Pass
Public key is present & not revoked
The p= tag holds a key — an empty p= means the key has been revoked.
Pass
Key type k=rsa is supported
RSA and Ed25519 are the key types receivers accept under RFC 6376.
Pass
Key length is 2048-bit
2048-bit RSA is the recommended strength. 1024-bit still validates but is considered weak.
Pass
Not in testing mode
No t=y flag — receivers enforce this signature rather than treating it as a test.
Pass
Public key is valid Base64
The p= value decodes to a well-formed DER public key.
Pass
Record tags
4 tags
TagNameValueStatus
v Version DKIM1 Required
k Key type rsa Optional
p Public key MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAvWyk…CQIDAQAB Required
n Notes 2048,1452627113,1468351913 Optional
Public key (Base64)
MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAvWyktrIL8DO/+UGvMbv7
cPd/Xogpbs7pgVw8y9ldO6AAMmg8+ijENl/c7Fb1MfKM7uG3LMwAr0dVVKyM+mbk
oX2k5L7lsROQr0Z9gGSpu7xrnZOa58+/pIhd2Xk/DFPpa5+TKbWodbsSZPRN8z0R
Y5x59jdzSclXlEyN9mEZdmOiKTsOP6A7vQxfSya9jg5N81dfNNvP7HnWejMMsKyI
MrXptxOhIBuEYH67JDe98QgX14oHvGM2Uz53if/SW8MF09rYh9sp4ZsaWLIg6T34
3JzlbtrsGRGCDJ9JPpxRWZimtz+Up/BlKzT6sCCrBihb/Bi3pZiEBB4Ui/vruL5R
CQIDAQAB
Raw TXT record
selector1._domainkey.outlook.com.   3600   IN   TXT   "v=DKIM1;k=rsa;p=MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAvWyktrIL8DO/+UGvMbv7cPd/Xogpbs7pgVw8y9ldO6AAMmg8+ijENl/c7Fb1MfKM7uG3LMwAr0dVVKyM+mbkoX2k5L7lsROQr0Z9gGSpu7xrnZOa58+/pIhd2Xk/DFPpa5+TKbWodbsSZPRN8z0RY5x59jdzSclXlEyN9mEZdmOiKTsOP6A7vQxfSya9jg5N81dfNNvP7HnWejMMsKyIMrXptxOhIBuEYH67JDe98QgX14oHvGM2Uz53if/SW8MF09rYh9sp4ZsaWLIg6T343JzlbtrsGRGCDJ9JPpxRWZimtz+Up/BlKzT6sCCrBihb/Bi3pZiEBB4Ui/vruL5RCQIDAQAB;n=2048,1452627113,1468351913"
Guide

Reading a DKIM record

DKIM (DomainKeys Identified Mail) lets a sending server sign outgoing mail with a private key. This DKIM record checker looks up the matching public key is published in DNS as a TXT record at <selector>._domainkey.<domain> , so receivers can verify the signature and confirm the message wasn't altered in transit.

The selector is the part you have to know — a domain can publish many keys (one per provider, or rotated over time), each under its own selector. There's no way to list them from DNS, so you supply the selector printed in a message's DKIM-Signature: header (the s= tag) or in your mail provider setup screen.

The record itself is a set of tag=value pairs: v=DKIM1 (version), k (key type — rsa or ed25519), and p (the Base64 public key). An empty p= means the key was revoked. Prefer 2048-bit RSA or Ed25519 — 1024-bit keys still validate but are considered weak.

This tool validates the DKIM DNS record and public key. It does not verify a specific email message signature; that requires the original message headers and body.

FAQ

Frequently asked questions

What is a DKIM record checker?

A DKIM record checker looks up the public key published at selector._domainkey.domain. It validates the DKIM DNS TXT record, parses tags such as v, k, and p, and checks whether the public key is present and usable.

What is a DKIM selector?

A selector identifies which DKIM key a mail system used to sign a message. You can find it in the s= tag of a DKIM-Signature header or in your mail provider setup instructions.

Why is my DKIM record not found?

The selector may be wrong, the record may not have propagated, or the TXT value may be published at the wrong hostname. The expected hostname is selector._domainkey.example.com.

Does this verify an email message signature?

No. This tool checks the DKIM DNS record and public key. It does not verify a full email message signature because that requires the message headers and body.