Table of Contents
Summary
- Custom HTML templates for Teams Events email notifications must reference a verified domain in your Microsoft 365 tenant.
- Templates lacking a verified domain may stop functioning as expected after enforcement.
- No impact on organizations using default templates.
- Organizations should verify domain ownership and update template settings accordingly.
- Notification to Teams Events owners or template maintainers is recommended for proper alignment with the changes.
Admin Impact: Medium
User Impact: Medium
Release Start: 31 Jan 2026
Release End: 31 Jan 2026
Services: Teams
Category: Stay informed
Tags: Admin Action
History
2/18/2026 Item Added to Message Center
Microsoft Message
Introduction
To ensure reliable delivery of Teams Events email notifications—and to protect organizations using custom HTML templates—we’re enforcing a requirement that all templates reference a verified custom domain in your Microsoft 365 tenant. This improves deliverability, reduces spoofing risk, and aligns with modern email authentication standards. As previously communicated in MC1176301 (October 2025), templates not configured with a verified domain may no longer function as expected after enforcement.
When this will happen
Enforcement was fully rolled out January 31, 2026.
How this affects your organization
Who is affected:
- Organizations with Teams Premium licenses.
- Organizations using custom HTML templates for Teams Events email notifications.
What will happen:
- Custom HTML templates must reference a domain verified in your Microsoft 365 tenant.
- Templates without a verified domain may stop working as expected once enforcement begins.
- Custom formatting or branding may fail without the required configuration.
- No impact for organizations using default templates.
What you can do to prepare
- Verify or confirm ownership of the domain you want to use for product notifications in the Microsoft 365 admin center.
- Update Teams Events email template settings so your custom HTML references a verified domain.
- Allow up to 12 hours for global propagation after saving.
- Update internal documentation and notify Teams Events owners or template maintainers.
Learn more:
- Configure domain selection for Microsoft 365 product notifications
Compliance considerations
No compliance considerations identified, review as appropriate for your organization.