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Terme informatique

DKIM

A cryptographic signature added to the emails to verify their integrity and origin declared.

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Simple definition

DKIM allows the recipient to verify that an email has not been changed and that it has been signed by an authorized server of the domain.

Technical definition

The sending server signs some headers and the message body with a private key. The corresponding public key is published in DNS under a selector DKIM.

What is it used for ?

Strengthening email authentication and participating in policy DMARC.

Practical example

Microsoft 365 signs domain messages and the recipient recovers the public key in DNS to validate the signature.

Common issues

  • Key DNS absent
  • Invalid selector
  • Signature broken by message modification
  • Too old or too short key

DNS · SMTP · SPF · DMARC · Encryption

Key takeaway: This entry explains the general operation of the term. Exact settings may vary depending on software, vendors and environments.

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