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  • Hanna Korotka

Are You Taking the Necessary Steps for Email Authentication in 2024 to Ensure Your Online Safety on Safer Internet Day?

Celebrated on February 13th annually, Safer Internet Day underscores the collective effort required to enhance online security. In 2024, as digital communication complexities grow, the day’s principles spotlight the critical role of email authentication in safeguarding online interactions.


Email, a vital tool for professional communication, marketing, and sharing information, hinges on deliverability for its effectiveness. The reliability and security of reaching intended recipients are paramount, making email authentication a necessity for maintaining security and compliance for Microsoft 365 and Microsoft cloud environments. Microsoft and Google have underscored the increasing need for stringent email authentication to counter cyber threats and ensure email credibility.


With 2024's changes, Microsoft 365 email senders face hurdles with stricter security protocols from Google and Yahoo. Google's enhanced authentication requirements aim to curb spam, resulting in the rejection of non-compliant bulk emails. Similarly, Yahoo's tightened rules demand rigorous authentication.


Non-compliance repercussions often appear in the form of Non-Delivery Reports (NDR) such as:


Authentication Failure: 550-5.7.26 This mail is unauthenticated, which poses a security risk to the sender and Gmail users and has been blocked. The sender must authenticate with at least one of SPF or DKIM. For this message, DKIM checks did not pass and SPF check for [] did not pass with IP: [IPAddress].


Deferral from Yahoo: Remote server returned '550 5.4.300 Message expired -> 451 [RL01] Message temporarily deferred.'


Spam: 421-4.7.28 Our system has detected an unusual rate of unsolicited mail originating from your IP address. To protect our users from spam, mail sent from your IP address has been temporarily rate limited.


Understanding Email Authentication


Email authentication protocols, essential for managed compliance for Microsoft 365, ensure messages are legitimate and secure, crucial in combating spam and phishing. They include:

  • Sender Policy Framework (SPF): Validates emails sent from authorized servers, a key aspect of security and compliance for Microsoft cloud.

  • Domain Keys Identified Mail (DKIM): Verifies an email's integrity through a digital signature.

  • Domain-based Message Authentication, Reporting, and Conformance (DMARC): Enhances security and deliverability through SPF and DKIM, with reporting for email handling.


Implementing Email Authentication


Businesses enhancing deliverability in 2024 should:

  • Audit existing email authentication setups for gaps.

  • Update or implement SPF, DKIM, and DMARC records following best practices. For guidance, refer to our post on setting up these records in Microsoft 365.

  • Regularly monitoring deliverability and authentication reports for necessary adjustments, a key strategy in managed security for Microsoft cloud.



Outbound email authentication's role in deliverability is increasingly critical amidst growing digital threats and stricter email provider requirements. Adopting SPF, DKIM, and DMARC is vital for organizations relying on email communication. By proactively authenticating emails, businesses can protect their reputation, improve security, and ensure efficient, reliable message delivery.

To help you to have peace of mind knowing your business is secure, click here to schedule a Microsoft 365 Secure Score review with our experts today. We'll evaluate your current cybersecurity measures, identify potential vulnerabilities, and help you implement a strategic security plan to keep your company safe.

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