6/25/2025 Important update regarding the cloud hosted Mailbox External Recipient Rate Limit: In order to reduce the impact on customers, Microsoft has again decided to delay the rollout of the cloud ...
Updated Jun 25, 2025
Version 14.0
Blog Post
IanMcDonald
Microsoft
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The External Recipient Rate Limit will only be applicable to cloud-hosted mailboxes and it will be applied per cloud-hosted mailbox. If you are relaying through us from an on-premises mailbox, this doesn't apply to you.
For cloud-hosted mailboxes that are using 3rd parties email gateways, we will account (and not inappropriately count) for these scenarios. We won’t count intratenant mail against the External Recipient Rate Limit even if it routes out of ExO then back in. We also won’t double-count messages or recipients when the message is sent out of ExO, routes back in, then routes out of ExO again and to the final destination. However, if your cloud hosted mailbox routes any external mail to a 3rd party gateway, then these mails to external recipients would be counted.
For finding out which of your cloud-hosted mailboxes are sending to over 2,000 external recipients, we are planning a report that will be available by end of 2024 which will detail current volume metrics for the tenant and usage per mailbox and provide other admin optics."