*For this entry exists the more relevant or more recent entry (MC1302901)
check before: 2025-10-01
Product:
Bookings, Entra, Exchange, Microsoft 365 admin center
Platform:
Online, World tenant
Status:
Change type:
Feature update, Admin impact
Links:
(MC1302901)
Details:
Summary:
Microsoft will throttle outbound emails sent from default onmicrosoft.com domains starting mid-October 2025, limiting to 100 messages per organization per 24 hours. This encourages use of custom domains. Internal emails remain unaffected. Admins should switch to custom domains and update related configurations accordingly.
Details:
Introduction
To improve email deliverability and reduce abuse, Microsoft is introducing outbound email throttling for default MOERA domains (e.g., contoso.onmicrosoft.com). These domains are intended for initial tenant setup and testing-not for regular email traffic. This change encourages organizations to adopt custom domains with independent reputations.
When this will happen
General Availability (Worldwide): Rollout begins mid-October 2025 and will complete by early June 2026. Rollout timing will vary based on organization seat counts. For detailed rollout information, refer to Limiting Onmicrosoft Domain Usage for Sending Emails.
Change Category:
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Scope:
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Release Phase:
Created:
2025-08-29
updated:
2025-08-29
Task Type
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Docu to Check
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MS How does it affect me
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MS Preperations
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MS Urgency
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MS workload name
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summary for non-techies**
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Direct effects for Operations**
Please, look at the most relevant linked item for details
explanation for non-techies**
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** AI generated content. This information must be reviewed before use.
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