Microsoft has announced a significant change in how it licenses and enforces access to Exchange Web Services (EWS). This is a crucial Application Programming Interface (API) used by many external systems to integrate with the Exchange Online platform.
Effective March 1, 2026, EWS access will be permanently blocked for mailboxes that do not formally have licensing rights to use this service. This change directly impacts organizations using cheaper licensing plans that have previously been unofficially utilizing EWS.
Who is affected by this Microsoft change starting March 1, 2026?
The change affects users with the following licenses:
- Exchange Online Kiosk
- Microsoft 365 / Office 365 F1
- Microsoft 365 / Office 365 F3
These licenses have never formally provided access to EWS, but the restriction was not enforced until now.
If your employees or mailboxes are covered by one of these licenses and they rely on EWS integrations, attempts to use EWS after March 1, 2026, will result in an HTTP 403 (Forbidden) error. This is a critical time for planning migration or license updates.
What remains unchanged?
For the users covered by the specified licenses, daily email work will still be possible to a certain extent. The following remains unchanged:
- Outlook on the web (Outlook Web) and the new version of Outlook (based on web technology) will function normally for these licenses within the scope of features that were previously available.
- Users will still be able to use Teams, SharePoint, and Office online applications.
- Full Exchange email in classic Outlook (desktop) is not available in these plans – this change does not alter that. Impact on Integrations and External Applications
This is the most important point for IT administrators and business owners. EWS is often the silent hero that connects Exchange mailboxes with critical business systems.
The risk primarily concerns
- CRM Systems. Integrations that synchronize emails, contacts, or calendars between the CRM system and Exchange Online.
- Data Archiving Systems. Solutions that retrieve email messages for compliance and long-term storage purposes.
- Email Migration Systems and any solutions utilizing the EWS API.
If your organization uses such integrations, it will be necessary to assign a license with EWS rights.
What should you do?
The date March 1, 2026, may seem distant, but in the context of auditing, budget planning, and potential system migration, this is the last call for action. Do not allow critical CRM or archiving systems to stop working!
If you need EWS or full email access in Outlook, you must assign a license with EWS rights, for example:
• Exchange Online Plan 1 or 2
• Microsoft 365 / Office 365 E1, E3, or E5
Contact us! We will help you conduct an audit of EWS usage in your organization, identify affected mailboxes, and plan an effective license update strategy to avoid downtime and the HTTP 403 error.