SPF and DKIM alone are not enough to protect brands from cyberattacks. It is extremely important to implement DMARC in alignment with SPF and DKIM protocols.
DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email authentication standard that determines whether an email is authentic or not. It decides the authentication status of an email by combining DKIM and SPF records. While providing visibility of the original source of an email from your domain, it ensures better deliverability and guarantees security against spoofing, phishing, and impersonation attacks.
DKIM and SPF
DomainKeys Identified Mail (DKIM) is an anti-tamper protocol that ensures the secure transit of your email message. DKIM uses digital signatures to confirm whether the email was sent by an authentic domain.
SPF or Sender Policy Framework (SPF) 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. As the email is being delivered, SPF allows the recipient email server to verify whether the email claiming to be from a specific sender is actually from an IP address that is authorized to send emails on the domain's behalf.
The following points describe the DKIM’s relationship with SPF and DMARC:
• Through SPF, senders can specify which IP addresses are allowed to send emails using a specific domain.
• DKIM provides an encryption key as well as a digital signature that ensures that an email message is not forged or tampered with.
• DMARC combines SPF and DKIM authentication procedures and allows domain owners to specify how an email from their domain should be handled if it fails the authentication.
Now that we’ve seen what these protocols can do, let’s look at what they CANNOT do and why they’re not enough!
SPF LIMITATIONS
• The sender's address, which is accessible to the user, is not protected by SPF. All SPF does is let the domain owner specify which email servers are permitted to send emails using that particular domain.
• SPF authorization does not have a significant impact on the delivery of emails. SPF protocols validate the sender's IP address and confirm whether it is authorized to send emails on the domain's behalf.
• The ‘-all’ policy has no effect on security but, instead, has a negative impact on message delivery. This tag tells the user to reject emails whenever there is a mismatch with the record.
• SPF must be configured even on mail servers of domains that are not used to send emails. This is because attackers continuously look for authorized domains that can be abused. Additionally, it is a good idea to employ a blocking policy for MX, A, and wildcard records that are not used to send emails.
• SPF is not self-sufficient. DKIM is required to forward email messages securely while DMARC is essential to prevent spoofing of the sender's address. Additionally, DMARC allows you to receive reports on SPF policy violations.
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DKIM LIMITATIONS
• The message envelope that contains the return path and message recipients is not covered by DKIM signatures.
• Because DKIM does not sign all sections of the message and only authorizes certain headers, malicious actors can forge the email by adding more header fields.
• The information validated by DKIM is only on the server-side. End users do not benefit much from the fact that an email is validated by DKIM.
• DKIM does not encrypt emails. It simply uses digital signatures to confirm whether the email was sent by an authentic domain.
• Emails fail DKIM when the sender does not have DKIM configured. One of the most common scenarios is when the email message comes from a legitimate third-party system that does not have DKIM configured. Therefore, emails failing DKIM authentication aren’t always spam.
This is exactly why DKIM and SPF are not enough for email authentication. To guarantee the complete security of your emailing systems and acquire control of your domain’s activities, you will need to:
• Implement DMARC in alignment with DKIM and SPF.
• Enable visual identification with BIMI. This boosts brand recall and creates outreach while protecting customers from getting phished via fake emails.
• Implement TLS encryption of emails with MTA-STS.
• Detect and mitigate email delivery issues by enabling TLS-RPT.
With the increase in the number of phishing and spoofing attempts daily, a holistic approach is required to fend ourselves against ruthless and nefarious hacking groups. DMARC in alignment with DKIM and SPF can be our biggest line of defense against these attacks. In addition to implementing these authentication protocols, it is recommended to encode your emails using the latest standards. Further, having a strong brand identity prevents cyberattacks from succeeding.
To learn more about DMARC, DKIM, and SPF, head to https://emailauth.io/