Reminder: Update Email Configurations for Viva Engage Email Domain Migration

Starting October 6, 2025, Viva Engage emails will switch from @yammer.com domains to tenant-specific @engage.mail.microsoft domains. Admins must update mail flow rules, spam filters, and safe sender lists accordingly to ensure proper email delivery and filtering. Users should update personal inbox rules if needed. Introduction This is a reminder based on our previous communication (MC1117814) regarding the Viva Engage email sender domain update. Please ensure your email configurations are updated, as we plan to roll out the new email domains for your tenant starting Monday, October 6, 2025. When this will happen: Rollout begins: Monday, October 6, 2025 Expected completion: Tuesday, October 7, 2025 Applies to U.S. and EU tenants currently receiving messages from @yammer.com and @eu.yammer.com. How this will affect your organization: All emails from Viva Engage will now come from a new domain instead of yammer.com or eu.yammer.com The exact sender domain depends on the data residency for your Viva Engage network: US geo: from @yammer.com to @engage.mail.microsoft EU geo: from EU​.yammer.com to @eu.engage.mail.microsoft In addition to the domain change, Viva Engage email addresses will now include a tenant-specific prefix to help differentiate your organization’s environment such as test and production tenants. For example, fabrikam.onmicrosoft.com will result in a “fabrikam” prefix. Continuing with this example, sender addresses may include: [email protected] – for digest emails, leader identification, community expert identification, delegate notifications and others. [email protected] – for community posts, storyline updates, and other user activity notifications. [email protected] – for leadership announcements and other broad communications. For networks in the EU geo, you should change the sender domain in the examples above to [email protected], etc. These changes affect all Viva Engage emails, including notifications, announcements, and digests. What you need to do to prepare: Admins should review these configurations before and during rollout: Email Transport / Mail Flow Rules: Update any rules referencing @yammer.com (or EU.yammer.com) to also include @engage.mail.microsoft (and EU.engage.mail.microsoft) so encryption, forwarding, or redirection rules keep working. Security Filters: Add the new domains to spam filters or allowlists if they were previously trusted.  Outlook Inbox Rules: Notify users to update personal rules that filter by domain (e.g., […]

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