How is DKIM related to SPF and DMARC?

How is DKIM related to SPF and DMARC?

Organizations must understand that to secure their money and data, it is inevitable that they need to set up email authentication. However, email authentication protocols can be tricky and complicated for beginners.


DKIM, SPF, and DMARC are all forms of email authentication that ensure better email deliverability and email security. Let’s understand how these protocols are related and how different they are from each other.


DKIM (DomainKeys Identified Mail) is an anti-tamper protocol that secures your emails while in transit. It uses digital signatures to confirm whether the email was sent by an authentic domain.

The first DKIM action occurs on the server that sends a DKIM signed email, while the second takes place on the recipient server that checks DKIM signatures on incoming emails. The entire process is made possible by a pair of private and public keys. 

The private key is kept secret and safe either on your own server or with your ESP. The public key, on the other hand, is added to the DNS records of your domain to broadcast to the world and help verify your emails. This is done by providing a digital signature for the email. Once the receiver verifies that an email is signed with a valid DKIM signature, it’s clear that the integrity of the email is preserved. 

DKIM signatures are not visible to end-users and the validation occurs at the server level.




SPF (Sender Policy Framework) is an email authentication protocol that allows the owner of a domain to specify which email servers are permitted to send emails from their domain. 


SPF detects forged sender addresses while the email is being delivered. It is confined to detecting a forged sender claim in the email's envelope, which is used when the email bounces. It can only be used in conjunction with DMARC to identify if the visible email address has been forged (email spoofing), is a common phishing attack, or is a spam technique to steal your credentials. 


The DNS records for a domain publish a list of authorized hosts and IP addresses for that domain. During email delivery, SPF uses these DNS records to allow the recipient server to verify that an email claiming to be from a given domain has been sent from an IP address authorized by the domain's administrators. 


Emails sent from servers that do not have SPF implemented are more likely to be flagged as spam by recipient mail servers. We recommend that you set up DKIM and DMARC in addition to SPF. These authentication techniques increase the security of your domain and ensure that messages sent from it are delivered correctly.


Now that we have seen what SPF and DKIM do and how they ensure the sanctity and legitimacy of outbound emails, let’s look at how DMARC works in alignment with both protocols and prevents spoofing, phishing, and impersonation.




What is DMARC -(Domain-based Message Authentication, Reporting, and Conformance) is an email authentication standard or protocol that determines whether an email is authentic or not. It relies on SPF and DKIM protocols to decide the authentication status of an email. It provides visibility of the original source of an email and not just the sender ID mentioned in the address bar. It ensures better email deliverability and top-notch security to ensure that your domain does not fall prey to spoofing, phishing, and impersonation attacks.


It is crucial to understand why these authentication protocols have become increasingly eminent in the cyber world and email ecosystem. 


Phishing attacks led to an estimated $1.9 billion in losses in 2020. Organizations worldwide suffered major data breaches and spoofing attacks in the last couple of years. The data and money that is lost are sometimes irrecoverable. It is, therefore, of utmost importance that brands set up stringent email protocols to better protect their data and money. 


Apart from guaranteeing the security of your email channels, authentication protocols provide many advantages to organizations and businesses. We’ve compiled a list of the most important ones.


Email authentication:

  • Secures your brand image by preventing unauthenticated parties from sending email communications using your domain. 
  • Builds a steady strategy for managing messages that fail the authentication check, making your email systems safer and more dependable.
  • Allows you to use the same modern technology that large companies use to deliver emails both internally and externally. 
  • Improves domain reputation and email deliverability. With SPF, domains can fend off impersonation attempts and email spoofing. 
  • Identifies emails that don’t spam and don't need to be filtered. With DKIM, a receiving system can maintain a whitelist of secure sending domains that can be kept locally or obtained from third-party certifiers. It can then skip the filtering of signed emails from those whitelisted domains and filter the remaining ones more aggressively. 

DMARC works in alignment with SPF and DKIM to secure email channels. SPF allows the domain owner to specify which addresses are authorized to send an email on their behalf. DKIM, on the other hand, uses an encrypted signature to verify if an email sender is exactly who they claim to be. 


Both SPF and DKIM protocols produce individual authentication identifiers that help authenticate and validate emails in various ways. If they have been implemented, their receiving server can identify who an email is from but does not know if email traffic is properly configured, which is why they cannot take any action against emails that fail authentication. 


DMARC combines the results of SPF and DKIM to accurately identify if an email is from either an authorized sender or a fraudulent impersonator. Therefore, it is well-equipped to actively block cyberattacks by enforcing a DMARC policy. With DMARC, you can instruct receiving servers on how to deal with emails that use your domain by setting your own distinct policies. Hence, it is recommended to use all these protocols together to be better protected against cyberattacks.

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Published by Ariya Rathi


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