Why DMARC Matters More Than Ever Under Microsoft’s New Email Security Standards

As of May 2025, Microsoft has begun strictly enforcing new email authentication requirements across Outlook. These changes directly impact any organisation sending email to Outlook users. Without the proper safeguards in place – especially DMARC, your messages may be flagged as suspicious, land in the Junk folder, or be blocked outright. This follows similar, recent policy changes by Google and Yahoo.

DMARC Is Now Mission-Critical

To combat phishing, spoofing, and spam, Microsoft mandates full alignment with three core authentication standards:

· SPF (Sender Policy Framework): Verifies that emails come from servers you’ve authorised.

· DKIM (DomainKeys Identified Mail): Uses cryptographic signatures to ensure messages haven’t been altered in transit.

· DMARC (Domain-based Message Authentication, Reporting & Conformance): Sits on top of SPF and DKIM to define how recipients should handle messages that fail authentication and provides visibility into who’s sending email on your domain’s behalf.

While SPF and DKIM are foundational, DMARC is the policy layer that brings them together. Without DMARC, even correctly signed messages may be vulnerable to spoofing and abuse. With DMARC, you control enforcement, gain detailed reporting, and build trust with mailbox providers like Microsoft.

Are you ready for the change?

The National Cyber Security Centre in the UK has a handy tool for checking to see if your domain is ready for DMARC enforcement. Use this link to check your domain:

https://checkcybersecurity.service.ncsc.gov.uk/email-security-check/form

Avoid the Junk Folder – Start with DMARC

Staying compliant begins with auditing your DNS records. A properly configured DMARC record should be aligned with both SPF and DKIM. Microsoft’s guidelines recommend prioritising this audit to identify gaps and misconfigurations.

DMARC implementation isn’t just a checkbox, it requires thoughtful setup, alignment, and ongoing monitoring. The good news? You don’t have to go it alone.

Protect Your Domain. Protect Your Brand.

Email that isn’t authenticated with DMARC can be exploited by bad actors, damaging your reputation and deliverability. Synergy helps you implement DMARC with confidence, ensuring your domain is protected, your emails are trusted, and your messages reach the inbox. Contact us today to schedule a DMARC assessment and take the first step toward securing your email domain.