What the heck is Cinco De Microsoft? Why, today is. Monday, May 5, 2025, the date when, as announced by Microsoft, non-compliant bulk email messages sent to Microsoft consumer mailboxes (hotmail.com, live.com, outlook.com, etc.) will now be rejected.
If you’re sending emails, you’re sending some of them to Microsoft mailboxes. They’re one of the top mailbox providers, in both the consumer and corporate email spaces. (Though, today, Microsoft indicates that this applies to consumer mailboxes; they do mention that in the future, this will apply to corporate mailboxes, too.)
Thus, if you want to keep sending emails successfully, you’ll need to comply with these new Microsoft requirements, starting today.
Microsoft has posted an announcement, with updated requirements and FAQs. Find it here.
What Changed?
If you’ve been following along with this saga since the first announcement of these updated sending requirements (on April 2nd), you hopefully already noticed that Microsoft updated those updated requirements at the end of April, changing their enforcement plans. The old plan was to route non-compliant email messages to the junk or spam folder. That is no longer the case. Microsoft is saying that they plan to REJECT non-compliant mail instead.
Back in July, 2024, I asked, Is Microsoft getting on the Yahoogle bus? If you know what that means, then you know that the answer is yes! Microsoft not only got on the bus, but they’ve grabbed the wheel and with their jump straight to rejection-based enforcement, they’re helping to significantly improve the safety and security of the email ecosystem.
Get Informed
If you’re looking for an updated overview of what’s going on and what’s changed, I put together a Valimail video on Friday, May 2, where I walked through the updated requirements and clarified their new intention to reject mail from bulk senders not in compliance. Find that video here or embedded below.
It Starts with Authentication
At the core of these new requirements, you will find email authentication: SPF, DKIM and DMARC are now mandated by Microsoft. Alignment (meaning that at least one of the email authentication domains must match the visible from domain) is also required.
Microsoft says that a DMARC policy of “p=none” is good enough to comply with today’s requirements – but keep in mind that this doesn’t protect your domain against phishing and spoofing. You need a DMARC policy of “p=quarantine” or “p=reject” for actual protection.
Don’t forget MAGY
MAGY (Microsoft, Apple, Google and Yahoo) email sender requirements are now approaching a level of parity that we’ve never seen before. This is a good thing for everybody involved in the email ecosystem; a standardized (or near-standardized) set of requirements makes it easy to know what you need to do to be able to send email messages successfully, and better compliance, along with improved sender practices, means an improved inbox experience (with hopefully less spam and phishing emails) for all.
Google and Yahoo announced the first wave of enhanced sender requirements way back in October 2023. And just before Microsoft announced these updated sender requirements in early April, 2025, Apple quietly upgraded their bulk sender “best practices” to “requirements” on their own postmaster page. Best practices are clearly converging.
Testing for Compliance
Steve Atkins’ aboutmy.email tester is a great way to determine if the email you’re sending is compliant. You’ll want to make sure you pass the SPF, DKIM, and “aligned authentication” checks, for starters. Much of the rest of these checks remain important; but that’s a level of detail too deep for this quick overview.
More Information and Don't Panic
Want to dive even deeper? I’ve got a link roundup here. And remember not to panic -- this shouldn't be something we should think of as scary. Pretty much every one of these email sender requirements were already out there as "best practices" that successful email senders were mostly in compliance with, even before today.
Those few edge cases where you don't have everything up to the level needed will be easy to find any fix; that's the good thing about rejecting non-compliant mail. Rejections are an active feedback mechanism to tell you when something is going wrong. Watch for spiking bounce rates at Microsoft, and when found, ensure that your first troubleshooting for compliance with these new requirements.
What the heck is Cinco De Microsoft? Why, today is. Monday, May 5, 2025, the date when, as announced by Microsoft, non-compliant bulk email messages sent to Microsoft consumer mailboxes (hotmail.com, live.com, outlook.com, etc.) will now be rejected.
If you’re sending emails, you’re sending some of them to Microsoft mailboxes. They’re one of the top mailbox providers, in both the consumer and corporate email spaces. (Though, today, Microsoft indicates that this applies to consumer mailboxes; they do mention that in the future, this will apply to corporate mailboxes, too.)
Thus, if you want to keep sending emails successfully, you’ll need to comply with these new Microsoft requirements, starting today.
Microsoft has posted an announcement, with updated requirements and FAQs. Find it here.
What Changed?
If you’ve been following along with this saga since the first announcement of these updated sending requirements (on April 2nd), you hopefully already noticed that Microsoft updated those updated requirements at the end of April, changing their enforcement plans. The old plan was to route non-compliant email messages to the junk or spam folder. That is no longer the case. Microsoft is saying that they plan to REJECT non-compliant mail instead.Back in July, 2024, I asked, Is Microsoft getting on the Yahoogle bus? If you know what that means, then you know that the answer is yes! Microsoft not only got on the bus, but they’ve grabbed the wheel and with their jump straight to rejection-based enforcement, they’re helping to significantly improve the safety and security of the email ecosystem.
Get Informed
If you’re looking for an updated overview of what’s going on and what’s changed, I put together a Valimail video on Friday, May 2, where I walked through the updated requirements and clarified their new intention to reject mail from bulk senders not in compliance. Find that video here or embedded below.It Starts with Authentication
At the core of these new requirements, you will find email authentication: SPF, DKIM and DMARC are now mandated by Microsoft. Alignment (meaning that at least one of the email authentication domains must match the visible from domain) is also required.Microsoft says that a DMARC policy of “p=none” is good enough to comply with today’s requirements – but keep in mind that this doesn’t protect your domain against phishing and spoofing. You need a DMARC policy of “p=quarantine” or “p=reject” for actual protection.
Don’t forget MAGY
MAGY (Microsoft, Apple, Google and Yahoo) email sender requirements are now approaching a level of parity that we’ve never seen before. This is a good thing for everybody involved in the email ecosystem; a standardized (or near-standardized) set of requirements makes it easy to know what you need to do to be able to send email messages successfully, and better compliance, along with improved sender practices, means an improved inbox experience (with hopefully less spam and phishing emails) for all.I break down MAGY email sender requirements in my 2025 MAGY Sender Compliance Guide right here on Spam Resource.
Google and Yahoo announced the first wave of enhanced sender requirements way back in October 2023. And just before Microsoft announced these updated sender requirements in early April, 2025, Apple quietly upgraded their bulk sender “best practices” to “requirements” on their own postmaster page. Best practices are clearly converging.
Testing for Compliance
Steve Atkins’ aboutmy.email tester is a great way to determine if the email you’re sending is compliant. You’ll want to make sure you pass the SPF, DKIM, and “aligned authentication” checks, for starters. Much of the rest of these checks remain important; but that’s a level of detail too deep for this quick overview.More Information and Don't Panic
Want to dive even deeper? I’ve got a link roundup here. And remember not to panic -- this shouldn't be something we should think of as scary. Pretty much every one of these email sender requirements were already out there as "best practices" that successful email senders were mostly in compliance with, even before today.Comments
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