Microsoft has announced the indefinite cancellation of its Mailbox External Recipient Rate Limit in Exchange Online, reversing a previously planned restriction on bulk email sending.
The decision comes after significant customer feedback highlighting operational disruptions caused by the proposed limitation.
The tech giant’s Exchange Online Transport Team confirmed on January 6, 2026, that the external recipient rate limit would no longer be implemented.
This reversal addresses widespread concerns among organizations that rely on bulk email capabilities for legitimate business operations.
Microsoft stated that customers reported the limitation created “significant operational challenges,” particularly given the limited bulk sending tools currently available in the market.
The company emphasized that this decision reflects its commitment to balancing security and usability without disrupting essential business workflows.
The Mailbox External Recipient Rate Limit was initially designed to address two primary security concerns: Combating abuse of Exchange Online customers through spam and malicious email activity.
Preventing misuse by line-of-business (LOB) applications sending bulk email through the platform. However, Microsoft recognized that implementing the restriction would negatively impact legitimate business operations.
Rather than imposing blanket limitations, the company plans to develop “smarter, more adaptive approaches” to protect its service while respecting operational requirements.
What Remains Unchanged
While the external recipient rate limit is canceled, Microsoft confirmed that other restrictions remain in place. The Recipient Rate Limit and Tenant-level External Recipient Rate Limit, as outlined in Exchange Online’s service documentation, remain in effect.
These measures maintain baseline protections against abuse while preserving customer functionality. Microsoft pledged to continue listening to customer feedback and developing alternative security solutions.
The company aims to make Exchange Online “secure, reliable, and customer friendly” through future innovations rather than restrictive rate limiting.
Organizations managing bulk email campaigns in Exchange Online can continue operations under existing policies, with no additional sender restrictions anticipated in the immediate future.
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