Microsoft’s bulk sending requirements for 2025
Blog post from Resend
In early 2024, Gmail and Yahoo set the standards for bulk email senders, and Apple followed with strict requirements. Now, as of May 5, 2025, Microsoft has implemented new rules for high-volume email senders targeting bulk messages such as newsletters and promotional emails. These requirements apply to those sending 5,000 or more messages per day to consumer Microsoft domains like outlook.com, hotmail.com, and live.com, similar to Gmail and Yahoo's thresholds. The regulations mandate the use of SPF, DKIM, and DMARC for message authentication, with failure resulting in rejected emails. Bulk emails must also feature a clearly visible unsubscribe link, though Microsoft doesn't insist on a one-click experience. Additionally, a low spam complaint rate of under 0.3% is required, and valid sender addresses must be maintained. These changes are part of a broader shift towards stronger email authentication and better unsubscribe handling, enhancing the overall reliability of emails. Platforms like Resend offer built-in tools to help users comply with these standards, ensuring efficient mail management and real-time monitoring of metrics such as complaints and bounces.