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What is DKIM (DomainKeys Identified Mail)? E-mail sender authentication technology
Introduction
DKIM (DomainKeys Identified Mail) is an email authentication method that helps verify the authenticity of an email’s sender. It is a widely adopted technology used to prevent email spoofing and improve email deliverability. In this blog post, we will explain the concept of DKIM, how it works, and its significance in ensuring the trustworthiness of email communication.
Understanding DKIM
DKIM is a cryptographic method that allows the recipient to verify that an email originated from the indicated source and that it has not been modified in transit. It works by appending a digital signature to the email header, which can be verified using a public key published in the sender’s DNS records.
How DKIM works
1. Sender’s Domain Signing: The email originator signs the outbound email with a private key, which is stored on their mail server. The private key generates a unique signature for each email.
2. DKIM Signature Insertion: The server inserts the DKIM signature into the email header. The signature includes information about the signing domain, the algorithm used, and the selector, which is a string that helps locate the correct public key for verification.
3. DNS Record Publication: The sender publishes a DNS TXT record containing the public key corresponding to the private key used for signing. This allows the recipient to retrieve the public key for verification.
4. Email Transmission: The email is sent over the internet, and the recipient’s server receives it.
5. DKIM Verification: The recipient’s mail server retrieves the DKIM signature from the email header and extracts the signing domain and selector.
6. Public Key Retrieval: The recipient’s server retrieves the sender’s public key from the DNS records by combining the signing domain and selector.
7. Signature Verification: Using the retrieved public key, the recipient’s server verifies the DKIM signature. It verifies the cryptographic integrity of the email and confirms that it has not been tampered with.
8. Delivery Decision: Based on the DKIM verification result, the recipient’s server makes a policy decision. For example, if the DKIM signature is valid, the email is more likely to be considered authentic, leading to improved deliverability.
Benefits of DKIM
1. Email Integrity: DKIM ensures that the email has not been modified during transit, providing assurances of its integrity.
2. Sender Authentication: By verifying the DKIM signature, recipients can trust that the email comes from a legitimate source, reducing the risk of phishing and spoofing.
3. Improved Deliverability: Email providers take DKIM into consideration when deciding whether to deliver a message to the inbox or mark it as spam. Valid DKIM signatures increase chances of successful email delivery.
Conclusion
DKIM plays a crucial role in email sender authentication. By digitally signing emails, DKIM allows recipients to verify the authenticity and integrity of messages. This technology helps protect against email forgery and enhances trust in email communication. Implementing DKIM can significantly improve deliverability and reduce the likelihood of phishing attacks.
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