ChangeIntelIT change radar
Public mode

No access to your tenant or devices. Every item links to its source. What this means

Some sources, documents or advisories need attention: 272/272 feeds/APIs · 469/469 docs · 8/9 advisories · checked 17:51 UTC Customize Public modeDiscuss ChangeIntel on Discord
MC787382 Stay informedUpdated messageFeature updateAdmin impact

Exchange Online to introduce External Recipient Rate Limit

From Microsoft 365 Message Center Archive by Merill Fernando · Microsoft may not have sent this notice to your tenant.
Exchange Online
Microsoft 365 admin center

Rollout

Rollout dates are often only in the text. When Microsoft moves them, the change shows under "What changed".

Schedule dates changed in the text

Date phrases in schedule sentences differ between the versions this installation saw
  • Seen 25 Jun 2025 October 2025, October 1st, 2025, January 2025, January 1, 2025, December 2025 → April 1st, 2026, October 2026, April 1, 2026, October 1, 2026
  • Seen 17 Dec 2024 October 2025, October 1st, 2025, April 2026

Read from date phrases in Microsoft's text, not from notice metadata. A changed phrase can be a moved rollout, a new milestone or just rewording; "What changed" below shows which.

What the notice says

Microsoft’s text, safely structured

Updated January 6, 2026: To ensure the best customer experience we have decided not to proceed with the rollout of this limit. Please see https://techcommunity.microsoft.com/blog/exchange/exchange-online-canceling-the-mailbox-external-recipient-rate-limit/4483498 for more information. We apologize for any inconvenience this may have caused and thank you for your patience.

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 hosted Mailbox External Recipient Rate Limit (MERRL) by ~six months. The MERRL will go into enforcement in April 2026 for trial tenants and new tenants if the tenant is provisioned on/after April 1st, 2026. In April 2026, the Exchange Admin Center Report will be available for tenant admins to review Sender mailbox data on external recipient volume. In October 2026, the MERRL will go into enforcement for all cloud hosted mailboxes in the WWMT environment including existing tenants.

Please refer to the ACS email documentation (Prepare an email communication resource for Azure Communication Services - An Azure Communication Services concept article | Microsoft Learn) or reach out to your Microsoft account team for further support in this journey.

Please note: We have made the decision to not proceed with this change for DoD, GCC, or GCC High organizations at this time. We will communicate via Message center when we are ready to proceed. The External Recipient Rate Limit will only apply to WWMT/Production.

Please refer to the ACS email documentation (Prepare an email communication resource for Azure Communication Services - An Azure Communication Services concept article | Microsoft Learn) or reach out to your Microsoft account team for further support in this journey.

________________________________________

Today, we are announcing that, beginning in April 2026 (previously October 2025), Exchange Online will begin enforcing an external recipient rate limit of 2000 recipients in 24 hours.

Exchange Online does not support bulk or high-volume transactional email. We have not enforced limiting of bulk email until now, but we plan on doing so with the introduction of an External Recipient Rate (ERR) limit. The ERR limit is being introduced to help reduce unfair usage and abuse of Exchange Online resources.

When this will happen

The new ERR limit will be introduced in 2 phases:

Phase 1 - Starting April 1, 2026, (previously October 2025) the limit will apply to cloud-hosted mailboxes of trial tenants and all tenants created after this date.

Phase 2 – Starting October 1, 2026, (previously April 2026) we will start applying the limit to cloud-hosted mailboxes of existing tenants.

How this will affect your organization

Exchange Online enforces a Recipient Rate limit of 10000 recipients for cloud-hosted mailboxes. The 2000 ERR limit will become a sublimit within this 10000 Recipient Rate limit. There is no change to the Recipient Rate limit, and both of these will be rolling limits for 24-hour windows. You can send to up to 2,000 external recipients in a 24-hour period, and if you max out the external recipient rate limit then you will still be able to send to up to 8,000 internal recipients in that same period. If you don't send to any external recipients in a 24-hour period, you can send to up to 10,000 internal recipients.

For example:

  • You use a cloud-hosted mailbox to send to 1,000 external recipients and 2,000 internal recipients at 6:00AM on Day 1, for a total of 3,000 recipients. You then send to another 1,000 external recipients at 8:00AM on Day 1. Because you sent to 2,000 external recipients, you will be blocked from sending to external recipients until 6:00AM on Day 2. During this period, you are able to send to up to 6,000 internal recipients, but for this example, let's assume that you don't.
  • At 6:00AM on Day 2, the 1,000 external recipients and 2,000 internal recipients sent at 6:00AM on Day 1 will no longer count toward the 24-hour limit calculation. Thus, from 6:00-8:00AM on Day 2, you can send to up to 9,000 total recipients (e.g., 9,000 internal or 8,000 internal plus 1,000 external).
  • If you don't send to any internal or external recipients during this period, then at 8:00AM on Day 2 you can again send to 10,000 recipients total with up to 2,000 of them being external recipients.

What you need to do to prepare

If you have a cloud-hosted mailbox that needs to exceed the ERR limit, you can move to Azure Communication Services for Email, which is designed specifically for high volume email sent to recipients external to your tenant.

What changed

Between archive captures, newest first

  1. Updated June 25, 2025: WeJanuary 6, 2026: To ensure the best customer experience we have updateddecided not to proceed with the content. Thankrollout of this limit. Please see https://techcommunity.microsoft.com/blog/exchange/exchange-online-canceling-the-mailbox-external-recipient-rate-limit/4483498 for more information. We apologize for any inconvenience this may have caused and thank you for your patience. Important update regarding the cloud hosted Mailbox External …

  2. Updated December 16, 2024:June 25, 2025: We have updated the content. Thank you for your patience. Important update regarding the cloud hosted Mailbox External Recipient Rate Limit: After carefully considering your feedback and understanding In order to reduce the need for additional time to adjust, impact on customers, Microsoft has again decided to delay the rollout of the cloud hosted Mailbox External Recipient Rate Limit (MERRL) by ~six months. The MERRL will go into enforcement in October 2025April 2026 for trial tenants and new tenants if the tenant is provisioned after Octoberon/after April 1st, 2025.2026. In October 2025,April 2026, the Exchange Admin Center Report will be available for tenant admins to review Sender mailbox data on external recipient volume. In AprilOctober 2026, the MERRL will go into enforcement for all tenant's cloud hosted mailboxes in the WWMT environment including existing tenants. Please refer to the ACS email documentation (Prepare an … Azure Communication Services - An Azure Communication Services concept article | Microsoft Learn),Learn) or reach out to your Microsoft account team for further support in this journey. Please note: We have made the decision to not proceed with this change for … to proceed. The External Recipient Rate Limit will only apply to WWMT/Production.   Please refer to the ACS email documentation (Prepare an email communication resource for Azure Communication Services - An Azure Communication Services concept article | Microsoft Learn),Learn) or reach out to your Microsoft account team for further support in this journey.   ________________________________________ Today, we are announcing that, beginning in January 2025,April 2026 (previously October 2025), Exchange Online will begin enforcing an external recipient rate limit of 2000 … ERR limit will be introduced in 2 phases: Phase 1 - Starting JanuaryApril 1, 2025,2026, (previously October 2025) the limit will apply to cloud-hosted mailboxes of trial tenants and all newlytenants created tenants. after this date.  Phase 2 - Between July and December 2025,– Starting October 1, 2026, (previously April 2026) we will start applying the limit to cloud-hosted mailboxes of existing tenants.   How this will affect your organization: Exchange Online enforces a Recipient Rate …

  3. Updated November 15,December 16, 2024: We have updated the content. Thank you for your patience. Important update regarding the cloud hosted Mailbox External Recipient Rate Limit: After carefully considering your feedback and understanding the need for additional time to adjust, Microsoft has decided to delay the rollout of the cloud hosted Mailbox External Recipient Rate Limit (MERRL) by ~six months. The MERRL will go into enforcement in October 2025 for trial tenants and new tenants provisioned after October 1st, 2025. In October 2025, the Exchange Admin Center Report will be available for tenant admins to review Sender mailbox data on external recipient volume. In April 2026, the MERRL will go into enforcement for all tenant's cloud hosted mailboxes including existing tenants. Please refer to the ACS email documentation (Prepare an email communication resource for Azure Communication Services - An Azure Communication Services concept article | Microsoft Learn), or reach out to your Microsoft account team for further support in this journey. We have made the decision to not proceed with this change for DoD, GCC, … to proceed. The External Recipient Rate Limit will only apply to WWMT/Production. Please refer to the ACS email documentation (Prepare an email communication resource for Azure Communication Services - An Azure Communication Services concept article | Microsoft Learn), or reach out to your Microsoft account team for further support in this journey. ________________________________________ Today, we are announcing that, beginning in January 2025, Exchange Online will …

  4. Updated May 31,November 15, 2024: We have made the decision to not proceed with this change for DoDDoD, GCC, or GCC High organizations at this time. We will communicate via Message center when we are ready to proceed. The External Recipient Rate Limit will only apply to WWMT/Production. Today, we are announcing that, beginning in January 2025, Exchange Online will …

    • Tags Feature update, Admin impact → Updated message, Feature update, Admin impact

    Updated May 31, 2024: We have made the decision to not proceed with this change for DoD or GCC High organizations at this time. We will communicate via Message center when we are ready to proceed. Today, we are announcing that, beginning in January 2025, Exchange Online will …

  6. · first version seen

Learn more

Links from the notice and their documentation checks

No related evidence found in this installation's recent collection. This does not establish that no announcement exists.

Not confirmed here

What this page cannot tell you
  • Whether your tenant is affected: this is Microsoft's notice, not a check of your settings.
  • 1 linked page has not been read yet.
ChangeIntel

An IT change radar: releases, security, known issues, retirements, documentation changes, and service status from public sources. Every item links to supporting evidence; dates and statuses can change after they are read.

Sources read 27 Oct 17:51 UTC · 272 of 272 readable · 270 fully read · documentation 469/469 current

No accounts or analytics; your preferences stay in your browser. Information, not advice. ChangeIntel is an independent tool and is not affiliated with or endorsed by Microsoft, Apple, Google, Broadcom (VMware), Jamf, Oracle, Mozilla, or any other vendor it covers. Product names are trademarks of their owners. Built by Evotec.