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Glossary Security

DKIM

DKIM (DomainKeys Identified Mail) adds a digital signature to outgoing email that receivers verify with a public key published in DNS.

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In more detail

The sending server signs selected headers and the body; the DKIM-Signature header names the domain (d=) and selector (s=) to look up. A valid signature shows the message came through a server authorised by that domain and was not changed in transit. It is one leg of DMARC.

Try these tools

DKIM Record Generator

Create an RSA or Ed25519 DKIM key pair in your browser, or use your own public key, and get the selector._domainkey TXT record.

Email Header & Security Analyzer

Paste raw email headers to identify the true sender, understand routing hops, and analyze email security protocols like SPF, DKIM.

See also

  • Glossary SPF
    SPF (Sender Policy Framework) is a DNS record listing which servers may send email for a domain.
  • Glossary DMARC
    DMARC is a DNS policy that tells receivers what to do with email that fails SPF and DKIM alignment, and where to send reports about it.
  • Glossary Digital signature
    A digital signature is a value computed from a message and a private key that proves who created it and that it has not been changed.
  • Guide How Email Authentication Works: SPF, DKIM and DMARC
    What SPF, DKIM and DMARC each check, what their DNS records look like.
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