check before: 2025-09-01
Product:
Exchange, Microsoft Viva, Microsoft Viva Engage, Outlook, SharePoint
Platform:
Online, World tenant
Status:
Rolling out
Change type:
Feature update, User impact, Admin impact
Links:
Details:
Summary:
Microsoft Viva Engage is migrating email sender domains from @yammer.com to @engage.mail.microsoft (and @eu.yammer.com to @eu.engage.mail.microsoft) between September 2025 and April 2026. This affects all Viva Engage tenants and users, requiring updates to mail flow rules, security gateways, and third-party integrations referencing the old domains.
Details:
[Introduction]
As part of the final phase of the Viva Engage rebranding, we're updating the email sender domains used for Viva Engage communications. This change ensures a consistent and secure brand experience across all surfaces and completes the transition from Yammer to Viva Engage.
This update was previously communicated in MC1117814, Microsoft Viva Engage | Email sender domain migration from @yammer.com to @engage.mail.microsoft, in September 2025.
[When this will happen:]
The email sender domain rollout began in early September 2025 for U.S. and EU tenants that were receiving messages from @yammer.com and @eu.yammer.com, respectively.
The rollout is expected to complete by mid‑April 2026.
A fallback/coexistence period will be in place between September 2025 and April 2026, during which some tenants will remain on the old experience while others transition to the new one.
Change Category:
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Scope:
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Release Phase:
Created:
2026-03-17
updated:
2026-03-17
Task Type
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MS How does it affect me
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summary for non-techies**
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Direct effects for Operations**
Email Deliverability Issues
If the email sender domain migration occurs without proper preparation, users may not receive important notifications and announcements due to outdated mail flow rules and security gateways that still reference the old @yammer.com domain.
- roles: Microsoft 365 Administrators, End Users
- references: https://techcommunity.microsoft.com/blog/viva_engage_blog/yammer-is-evolving-to-viva-engage/3738825
User Experience Disruption
Users with Outlook rules based on the old @yammer.com domain will find those rules ineffective, leading to missed emails and notifications, which can disrupt their workflow and communication.
- roles: End Users, IT Support Staff
- references: https://techcommunity.microsoft.com/blog/viva_engage_blog/yammer-is-evolving-to-viva-engage/3738825
Third-Party Integration Failures
Third-party integrations that rely on the old @yammer.com domain for classification or authentication may fail, causing disruptions in email routing, journaling, and archiving processes.
- roles: Microsoft 365 Administrators, Compliance Officers
- references: https://techcommunity.microsoft.com/blog/viva_engage_blog/yammer-is-evolving-to-viva-engage/3738825
Configutation Options**
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Potentional Risks**
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Data Protection**
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IT Security**
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explanation for non-techies**
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** AI generated content. This information must be reviewed before use.
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