How to comply with Microsoft’s new high-volume sender requirements?

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The business impacts of poor email deliverability

Following Google and Yahoo’s 2024 rollout of bulk sender requirements, Microsoft is now introducing its own email authentication rules for high-volume senders targeting Outlook.com domains.

From May 5, 2025, businesses sending more than 5,000 emails a day must comply—or risk having messages throttled, sent to spam, or blocked entirely.

-$15K

average revenue lost for every million emails sent

15.2%

legitimate marketing emails undelivered

$1M

additional revenue for every 1% increase in open rates seen by a Red Sift customer

64.6%

of businesses report deliverability issues directly impacted revenue or retention

Our free tool performs a comprehensive 6-point check to verify your readiness.

Validate your implementation of SPF and DKIM

Ensure your domain’s SPF and DKIM records are valid so DMARC can block spoofed emails.

Confirm SPF or DKIM alignment

Ensure the From: domain matches your SPF or DKIM domain, and note whether alignment is relaxed or strict.

Verify your DMARC policy

Publish a DMARC record at a minimum policy of p=none to prevent domain spoofing. Use Red Sift Investigate to access your current DMARC record.

Use a TLS connection for transmitting email

Confirm a TLS connection for encryption between two points, preventing a message from being read.

Ensure you have valid forward and reverse DNS (FCrDNS)

Ensure your sending IP matches its PTR record to confirm domain ownership.

Set up one-click subscribe and keep spam rate low

Enable one-click unsubscribe and keep spam <0.3%, monitored via Microsoft, Google, and Yahoo tools.

2025 guide to mastering Microsoft, Google, and Yahoo’s bulk email sender requirements

Microsoft's new rules require high-volume senders (5,000+ emails/day to Outlook.com domains) to implement specific email authentication protocols since May 5, 2025. Non-compliance risks message throttling, spam filtering, or complete blocking.

These are the technical standards you must implement:

  • SPF (Sender Policy Framework): Set up SPF for the sending domain and ensure the domain's DNS record accurately lists authorized IP addresses/hosts.
  • DKIM (DomainKeys Identified Mail): Set up DKIM to validate email integrity and authenticity.
  • DMARC (Domain-based Message Authentication, Reporting, and Conformance): Publish a DMARC policy for each domain that sends mail with at least a policy of "none" and align with either SPF or DKIM (preferably both).

FAQs

What are the new Microsoft requirements for high-volume senders?

Microsoft’s email sender requirements focus on authenticating your email-sending domain. The core requirements are:

  1. SPF (Sender Policy Framework): Set up SPF for the sending domain and ensure the domain's DNS record accurately lists authorized IP addresses/hosts.
  2. DKIM (DomainKeys Identified Mail): Set up DKIM to validate email integrity and authenticity.
  3. DMARC (Domain-based Message Authentication, Reporting, and Conformance): Publish a DMARC policy for each domain that sends mail with at least a policy of "none" and align with either SPF or DKIM (preferably both).

Why are these requirements coming into effect?

Microsoft has united forces with Google and Yahoo to ensure that global inboxes become safer and less spammy.

How can I get to DMARC enforcement?

To get to full enforcement, you can sign up for a 14-day free trial of Red Sift OnDMARC's automated DMARC application. Click here to learn more about OnDMARC.

When do I need to comply with these requirements?

Microsoft's requirements take effect on May 5, 2025. If you send 5,000+ emails per day to Outlook.com domains, you must be compliant by this date.

What happens if I don't comply?

Non-compliant senders will experience email throttling (delayed delivery), spam filtering (messages sent to junk folders), or complete blocking.

Do these requirements apply to all senders?

No - only high-volume senders sending 5,000+ emails per day to Outlook.com, Hotmail.com, and Live.com domains are required to comply.