---
title: "What is DKIM (DomainKeys Identified Mail)?"
url: "https://lookvalid.com/glossary/dkim.md"
canonical_url: "https://lookvalid.com/glossary/dkim"
last_updated: "2026-10-18"
type: "conceptual"
summary: "DKIM adds a digital signature to each email so the receiver can check that the message came from the signing domain and was not altered on the way."
related: ["https://lookvalid.com/glossary/spf.md", "https://lookvalid.com/glossary/dmarc.md", "https://lookvalid.com/products/email-domain-check.md"]
---

# What is DKIM (DomainKeys Identified Mail)?

DKIM adds a digital signature to each email so the receiver can check that the message came from the signing domain and was not altered on the way.

The sender signs selected headers and the body with a private key. The matching public key is published in DNS under a name that includes a "selector", which lets a domain run several keys at once.

A valid signature proves the signing domain vouches for the message. It does not say the signing domain is the same as the visible "From" domain until DMARC checks alignment.

## Related

- [What is SPF (Sender Policy Framework)?](https://lookvalid.com/glossary/spf.md)
- [What is DMARC?](https://lookvalid.com/glossary/dmarc.md)
- [Email Domain Check API](https://lookvalid.com/products/email-domain-check.md)