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Important Update: Teams Meeting Join URL Validation

Microsoft 365 Message Center Archive by Merill Fernando · Microsoft may not have sent this notice to your tenant.
Microsoft Teams
Microsoft 365 admin center

Rollout

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What the notice says

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Updated September 11, 2025: We have updated the timeline. Thank you for your patience. What and Who To enhance the security and integrity of Microsoft Teams meetings, we are introducing a new feature that validates Teams meeting join URLs. This update helps ensure that meeting links are not altered or rewritten by security products in ways that could render them unusable or flagged as malicious. This is applicable only when user Joins a meeting from Teams old calendar. Rollout Schedule Worldwide: September 30, 2025 GCC, GCC High, DoD: November 30, 2025 Impact on Your Organization Who is affected:Organizations that use security solutions to inspect or rewrite URLs, as well as users who join Microsoft Teams meetings through the Teams platform, will be affected by this update. What will happen: Users using New Calendar App:For new calendar app in Teams, Meeting joins will not be blocked instead users will be redirected to a outlook safelinks provider and again redirected to the destination rewritten Join url This feature is enabled by default and does not require admin configuration. For more information on New calendar in app in Teams follow this link: https://support.microsoft.com/en-us/office/get-started-with-the-new-calendar-in-microsoft-teams-98f3b637-5da2-43e2-91b3-f312ab3e4dc5  Old Teams Calendar App: Microsoft Teams will validate join URLs to ensure they have not been modified. If a join URL is rewritten or altered by a security product, it may be marked as malicious. Users will be prevented from joining meetings if URLs are not in their original format. This feature is enabled by default and does not require admin configuration. Microsoft's advanced email security platform, including Safe Links (URL inspection/rewriting), will not be impacted by this update. Safe Links Behavior:Does not rewrite the URLs behind the “Join Teams meeting” or “Join” buttons. Only rewrites URLs within the meeting invitation body. Any temporary rewriting (if applied) is removed by Exchange Online upon send/receive. Outlook Add-in Behavior If meeting links are rewritten via Outlook add-ins during meeting creation, there is no impact. Potential impact: This change may affect third-party security services that rewrite both the body URLs and the “Join” button URLs. Action required: No action is needed for customers using Safe Links. There is no requirement to add Teams meeting URLs to the Safe Links “allowed list.” For the customer using 3P solutions, they must ensure Teams join links are excluded from rewriting. Compliance Considerations: No compliance considerations identified, review as appropriate for your organization. Workaround: Switch to New calendar to unblock users from joining the Meeting. Platforms affected Only Microsoft Teams affected, other platforms like outlook web and win32, outlook mac remain unaffected.

What changed

Between archive captures, newest first

  1. Updated August 18,September 11, 2025: We have updated this message with additional information to clarify the Meeting joins experience. timeline. Thank you for your patience. What and Who To enhance the security … products in ways that could render them unusable or flagged as malicious. This is applicable only when user Joins a meeting from Teams old calendar. Rollout Schedule Worldwide: September 30, 2025 GCC, GCC High, DoD: November 30, 2025 Impact on Your Organization Who is affected: o Organizations using affected:Organizations that use security products thatsolutions to inspect or rewrite URLs, andas well as users who join Microsoft Teams meetings via meeting links.through the Teams platform, will be affected by this update. What will happen:Microsofthappen: Users using New Calendar App:For new calendar app in Teams, Meeting joins will not be blocked instead users will be redirected to a outlook safelinks provider and again redirected to the destination rewritten Join url This feature is enabled by default and does not require admin configuration. For more information on New calendar in app in Teams follow this link: https://support.microsoft.com/en-us/office/get-started-with-the-new-calendar-in-microsoft-teams-98f3b637-5da2-43e2-91b3-f312ab3e4dc5  Old Teams Calendar App: Microsoft Teams will validate join URLs to ensure they have not been modified. … altered by a security product, it may be marked as malicious. Users maywill be prevented from joining meetings if URLs are not in their original … This feature is enabled by default and does not require admin configuration. Note: Meeting joins will only be blocked if the join links are re-written in the calendar event details (Join URL). If the links are only re-written in the meeting description (or meeting body), it won’t impact the ability to join. Microsoft's advanced email security platform, including Safe Links (URL inspection/rewriting), will not be impacted by this update. Safe Links behavior: Does Behavior:Does not rewrite the URLs behind the “Join Teams meeting” or “Join” buttons. … Compliance Considerations: No compliance considerations identified, review as appropriate for your organization. Workaround: Switch to New calendar to unblock users from joining the Meeting. Platforms affected Only Microsoft Teams affected, other platforms like outlook web and win32, outlook mac remain unaffected.

    • Tags Feature update, User impact, Admin impact → Updated message, Feature update, User impact, Admin impact

    Updated August 13,18, 2025: We have updated this message with additional information to clarify the … High, DoD: November 30, 2025 Impact on Your Organization Who is affected: o Organizations using security products that inspect or rewrite URLs, and users who … Any temporary rewriting (if applied) is removed by Exchange Online upon send/receive. Outlook Add-in Behavior If meeting links are rewritten via Outlook add-ins during meeting creation, there is no impact. Potential impact: This change may affect third-party security services that rewrite both … solutions, they must ensure Teams join links are excluded from rewriting. Compliance ConsiderationsConsiderations: No compliance considerations identified, review as appropriate for your organization.

  3. Updated August 6,13, 2025: We have updated this message with additional information to clarify the … meeting description (or meeting body), it won’t impact the ability to join. Action Required/Recommendations Ensure that your security products doMicrosoft's advanced email security platform, including Safe Links (URL inspection/rewriting), will not be impacted by this update. Safe Links behavior: Does not rewrite Microsoftthe URLs behind the “Join Teams meeting” or “Join” buttons. Only rewrites URLs within the meeting joininvitation body. Any temporary rewriting (if applied) is removed by Exchange Online upon send/receive. Potential impact: This change may affect third-party security services that rewrite both the body URLs and the “Join” button URLs. Whitelist Microsoft Teams join URLs in your security software. Review your organization’s URL rewriting or inspection policies beforeAction required: No action is needed for customers using Safe Links. There is no requirement to add Teams meeting URLs to the Safe Links “allowed list.” For the rollout date. Communicate this change to your helpdesk and security teams.customer using 3P solutions, they must ensure Teams join links are excluded from rewriting. Compliance Considerations No compliance considerations identified, review as appropriate for your organization.

  4. Updated August 6, 2025: We have updated this message with additional information to clarify the Meeting joins experience. Thank you for your patience. What and Who To enhance the security and integrity of Microsoft Teams … This feature is enabled by default and does not require admin configuration. Note: Meeting joins will only be blocked if the join links are re-written in the calendar event details (Join URL). If the links are only re-written in the meeting description (or meeting body), it won’t impact the ability to join. Action Required/Recommendations Ensure that your security products do not rewrite Microsoft Teams …

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