Understanding Email Authentication Protocols in order to Improve Email Deliverability: SPF, DKIM and DMARC
Email communication is a vital part of our personal and professional lives. However, the convenience of email also comes with the challenge of ensuring the authenticity and security of email messages. To address this, three essential email authentication tools have emerged: SPF, DKIM, and DMARC.
In this post, we’ll explore the differences between them and why they’re crucial for email security.
SPF (Sender Policy Framework)
What is SPF?
SPF, or Sender Policy Framework, is an email authentication protocol that helps prevent email spoofing. It allows domain owners to define which mail servers are authorized to send email on behalf of their domain.
How does SPF work?
A domain owner publishes SPF records in their DNS settings.
Receiving email servers check the SPF records to verify if the sending mail server is authorized.
If the SPF check fails, the email may be marked as suspicious or rejected.
Why use SPF?
SPF helps prevent spoofed emails and improves email deliverability. By specifying authorized mail servers, it reduces the chances of emails being marked as spam or phishing.
DKIM (DomainKeys Identified Mail)
What is DKIM?
DKIM, or DomainKeys Identified Mail, is another email authentication technique that uses digital signatures to verify the authenticity of email messages. It allows recipients to check if an email’s content has been altered during transit.
How does DKIM work?
The sender’s mail server signs the email with a private key and adds a DKIM signature to the email header.
The recipient’s mail server retrieves the public key from the DNS records of the sender’s domain.
The email is verified by decrypting the DKIM signature with the public key and comparing it to the email’s content.
Why use DKIM?
DKIM provides an additional layer of email security by ensuring that messages haven’t been tampered with during transmission. It also helps build trust with recipients.
DMARC (Domain-based Message Authentication, Reporting, and Conformance)
What is DMARC?
DMARC, or Domain-based Message Authentication, Reporting, and Conformance, is a policy framework that combines SPF and DKIM to enhance email authentication. It also provides instructions on how to handle failed authentication attempts.
How does DMARC work?
Domain owners publish DMARC records in their DNS settings, specifying their preferred authentication methods (SPF and/or DKIM).
Receiving email servers check the DMARC records and follow the specified policy (e.g., quarantine or reject) for emails that fail authentication.
DMARC also includes reporting mechanisms to alert domain owners about failed authentication attempts.
Why use DMARC?
DMARC is the most comprehensive email authentication tool. It not only verifies email authenticity but also helps domain owners gain visibility into email traffic and protect their brand reputation.
In summary, SPF, DKIM, and DMARC are essential tools for ensuring the authenticity and security of email communication. While SPF and DKIM address specific authentication aspects, DMARC combines them and adds policy enforcement and reporting capabilities.
Implementing these email authentication protocols can protect your organization from phishing attacks, improve email deliverability, and enhance your brand’s trustworthiness in the digital world. By adopting SPF, DKIM, and DMARC, you’re taking a significant step toward a more secure and reliable email communication ecosystem.