Ready for Microsoft’s new high-volume sender requirements?

In under one minute, Red Sift’s free Investigate tool can determine if your email setup is ready for Microsoft’s new high-volume sender requirements.

Ready for Microsoft’s new high-volume sender requirements?

In under one minute, Red Sift’s free Investigate tool can determine if your email setup is ready for Microsoft’s new high-volume sender requirements.

SNAPSHOT

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

Red Sift Investigate
Breaking down Investigate’s comprehensive check
mail check

Validate your implementation of SPF and DKIM

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

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Confirm SPF or DKIM alignment

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

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Verify your DMARC policy

Publish a DMARC record at a minimum policy of p=none to prevent domain spoofing.

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Use a TLS connection for transmitting email

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

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Ensure you have valid forward and reverse DNS (FCrDNS)

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

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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.

Guide
Bulk sender guide

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

We’ve created this concise guide to steer any high-volume sender through Microsoft, Google and Yahoo’s 2025 rules. Inside you’ll learn:

This guide covers:

  • Who needs to comply and why the rules exist
  • The technical mandates you need to know, mapped to key deadlines.
  • Step-by-step guidance to reach compliance with ease, supported by Red Sift.
Bulk sender guide

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).

Microsoft has also recommended best practices for email senders, including: 

  • Use a compliant sender address: Make sure the “From” or “Reply-To” address is valid, matches your actual sending domain, and can receive replies.
  • Include a working unsubscribe link: Always provide a clear, easy way for recipients to opt out—especially for marketing or high-volume emails.
  • Maintain clean mailing lists: Regularly remove invalid or inactive addresses to reduce bounces, spam complaints, and unnecessary sends.
  • Be transparent with recipients: Use honest subject lines, accurate headers, and only contact users who’ve given clear consent to hear from you.
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. We are thrilled that these three email service providers are advocating for these changes, as strong email authentication has always played a critical role in email-based business operations.

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.

Get ready for Microsoft’s high‑volume sender requirements with Investigate