Prove Your Email Wasn't Tampered With (DKIM)

Why this matters

DKIM cryptographically signs each outgoing email so receivers can verify the message wasn't tampered with in transit. It ties your domain's reputation to individual messages and is required by major inbox providers for high-volume senders.

Try it yourself

1. Send a test email to Gmail and open 'Show original' — find the DKIM-Signature: header and confirm the d= tag matches your sending domain.
2. Look up your DKIM public key with dig TXT selector._domainkey.yourdomain.com and verify it returns a p= value (the public key).
3. Check what happens to the DKIM result if you forward a signed email — open headers on the forwarded copy and note whether the signature still passes or breaks.

References

• RFC 6376 — DomainKeys Identified Mail