Starting May 5, 2025, Microsoft Outlook is rolling out new rules for high-volume email senders - and if you're sending more than 5,000 emails a day, you're on the list.
These new requirements are all about cleaning up the inbox: better security, fewer shady senders, and (hopefully) more trust in the emails that do make it through. But for Marketing Operations teams, it means a little homework - and a lot of DNS updates.
Here’s the lowdown.
What’s changing?
Outlook’s cracking down on emails that aren’t properly authenticated. If your emails don't check all the right boxes, they’ll be sent straight to junk - or blocked altogether. Not ideal if you’re trying to hit your KPIs.
To stay on the right side of Microsoft's filters, you’ll need to make sure your sending domain passes:
SPF (Sender Policy Framework) – proves your domain is allowed to send the email
DKIM (DomainKeys Identified Mail) – signs your message to verify it wasn’t tampered with
DMARC (Domain-based Message Authentication, Reporting & Conformance) – ties it all together and tells inboxes what to do when something looks off
In short: if your email setup isn’t buttoned up, you’re about to have a deliverability problem.
What else Outlook wants from you
Along with the email authentication trio above, Microsoft also wants you to:
Use a valid “From” or “Reply-To” address—no shady throwaway inboxes
Include a working unsubscribe link (and yes, people will test it)
Keep your mailing lists clean—bounce-heavy lists are a red flag
Be honest in your subject lines—no clickbait nonsense
Why Marketing Ops should care
Because this affects every. single. campaign.
If your emails are flagged or junked, your nurture flows stall, your product launches flop, and your metrics take a nosedive.
Worse, you might not even know it’s happening until the complaints roll in. Compliance isn’t just for IT - it’s a core part of ops now.
What to do next
Here’s your quick to-do list to stay out of trouble:
Check your DNS records – Make sure SPF, DKIM, and DMARC are in place and properly aligned.
Clean your templates – Unsub links, clear sender info, no weird formatting—polish it up.
Scrub your lists – Remove the bounces, the spam traps, and anyone who hasn’t opened an email since 2021.
Monitor like a hawk – Watch your deliverability metrics. If something tanks, dig into it fast.
Bottom line?
If you want your emails to land in inboxes - not the void - these changes aren’t optional.
They're the new normal for sending at scale.
And if you need help navigating the chaos, well... maybe you should be listening to The MOPS Brief 😉
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