MC1251200 - Microsoft Viva Engage | Email sender domain migration from @yammer.com to @engage.mail.microsoft

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.

How this affects your organization:

Who is affected:

• All Microsoft Viva Engage tenants in U.S., EU, and global regions.
• All users who receive Viva Engage emails, including notifications, announcements, and digests.
• Microsoft 365 administrators who manage:
  • Exchange Online mail flow rules
  • Email security gateways
  • Journaling, archiving, or third-party mail integrations that reference the @yammer.com domain.

What will happen:

The sender domain for Viva Engage emails will change as follows:

• From @yammer.com to @engage.mail.microsoft for U.S. and global regions.
• From @eu.yammer.com to @eu.engage.mail.microsoft for European regions.

These new domains are secured with industry standard authentication protocols (e.g., SPF) to help prevent spoofing and ensure reliable delivery.

To enhance security and reduce cross-tenant spam, sender addresses will now include a tenant-specific prefix. You may see emails from:

• [email protected] (digests, delegates, leader identification, community expert, and other notifications)
• [email protected] (community, storyline, and activity notifications)
• [email protected] (leadership announcements)

These changes apply to all Viva Engage tenants, regardless of license tier (e.g., Viva P1, P2), and affect all Viva Engage emails, including notifications, announcements, and digests.

Third-party integrations (e.g., journaling, archiving, or routing systems) that rely on the @yammer.com domain for classification or authentication may be impacted. Any such configurations should be reviewed and updated to recognize the new domains.

Screenshot: An example of a new Viva Engage email notification sent from the updated @engage.mail.microsoft domain:

What you can do to prepare:

Review and update the following configurations:

• Transport rules and email gateways: Update any rules that reference @yammer.com to include the new domains.
• Exchange filtering: Ensure filtering rules remain effective with the new sender domains.
• Outlook rules: Inform users that any rules based on @yammer.com will no longer apply. Users can manually update or remove these rules.

No admin action is required unless your organization has custom configurations based on the old domain.

Learn more: Yammer is evolving to Viva Engage | Viva Engage Blog

Compliance considerations:

No compliance considerations identified, review as appropriate for your organization.