Microsoft Sender Requirements Enforced - How To Avoid 550 5.7.15 Rejections
Security Boulevard, Wednesday, April 30th, 2025
From May 5, 2025, Microsoft is strictly enforcing its email sender requirements. This move requires anyone sending over 5,000 emails per day to Outlook.com, Hotmail, and other Microsoft consumer mailboxes to properly authenticate their messages.
Failure to do so will no longer result in your emails landing in Junk, they'll be rejected outright with a '550 5.7.15 Access denied' error.
This applies to emails being sent to Microsoft's consumer email services - Outlook.com, Hotmail.com, and Live.com.
Key Takeaways:
> Microsoft will reject emails from high-volume senders (>5,000/day) that lack proper authentication starting May 5, 2025.
> Non-compliant emails will trigger the '550 5.7.15 Access denied' rejection error.
> To comply, senders must correctly implement SPF, DKIM, and DMARC.
> Domain misalignment, or missing authentication records, will cause hard rejections.
> PowerDMARC can simplify compliance and ensure your messages reach Microsoft inboxes.