If your business sends a lot of emails, there’s a new Microsoft email authentication update coming on 5 May 2025 that’s worth knowing about—especially if you send high volumes.

We’ve been following this closely with help from EasyDMARC’s breakdown of the update, one of the tools we use to protect our clients’ domains.

From that date, Outlook and other Microsoft services will start junking emails that aren’t properly authenticated. So, if your domain sends over 5,000 emails a day, you’ll need to have SPF, DKIM and DMARC set up and configured correctly.

Why Microsoft is Updating Email Authentication Rules

Why the sudden push for these protocols? Microsoft is stepping up email security. The goal is to build more trust in email communications and reduce spam, phishing, and spoofing. By enforcing stricter authentication, Microsoft hopes to keep Outlook inboxes safer for everyone.

Breaking Down Microsoft’s Email Authentication Protocols: SPF, DKIM & DMARC

Let’s take a quick look at what each of these protocols does:

• SPF – Think of it like a guest list for your email senders. It tells receiving servers which servers are allowed to send mail from your domain.

• DKIM – This one adds a digital signature to your messages. It helps verify that your emails haven’t been tampered with on the way to their destination.

• DMARC – This works alongside SPF and DKIM. It gives receiving servers instructions on what to do if something doesn’t check out. You’ll also get reports that show how your domain is being used—or abused.

All of this forms part of the Microsoft email authentication update. It’s designed to reduce spoofing and help make sure your legitimate messages reach their intended inboxes.

What Happens If You Don’t Follow Microsoft’s Email Rules?

From 5 May 2025, any unauthenticated emails from high-volume domains will start going straight to junk. That’s just the first step. Microsoft has said tougher enforcement is coming, including outright email rejection.

How Novo IT Can Support You Through Microsoft’s Email Update

Getting SPF, DKIM and DMARC set up can feel overwhelming, but we’ve got your back. At Novo IT, we help businesses secure their email systems and stay compliant. We’re partnered with EasyDMARC, a trusted provider of email authentication tools, to make setup smooth and stress-free.

We’ll help you get everything configured correctly, so your emails keep landing where they should—right in your clients’ inboxes.

Next Steps to Prepare for Microsoft’s Email Authentication Changes

Not sure if you’re already compliant? Or maybe you’ve heard of these protocols but haven’t had the time to sort them out. Either way, we’re here to help.

This Microsoft email authentication update is just one part of a bigger picture. If you’re ready to take a more secure approach to all your IT systems, check out our Cybersecurity Services to see how we can support your business.

Disclaimer: This article was created with the assistance of AI tools based on prompts and guidance provided by Novo IT Ltd.