Exchange Web Services Retirement: Configure Your Allow List

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The Exchange Web Services retirement timeline now has a hard cutoff that you can plan around.

On October 1, 2026, Microsoft starts blocking Exchange Web Services (EWS) requests to Exchange Online. Any tenant still set to EWSEnabled=Null gets flipped to False during this rollout. That single change cuts off every EWS application in your tenant at once.

Preparing Your Tenant Settings Before the August Deadline

Fortunately, you have a brief window to prepare. You must configure an approved allow list and set EWSEnabled=True before the end of August 2026. If you complete this step, Microsoft excludes your tenant from the automatic October 1 disablement.

However, if you miss this window, EWS will go dark for your applications immediately on day one. A related compliance deadline lands during the same month. You must update your EWS allow list to accommodate the Teams mobile calendar change, which also arrives in August 2026.

Simple Steps to Transition Your Legacy Integrations

Administrators should execute four key action items to prevent workflow disruptions:

  • Audit your system: Inventory every app, script, and integration still calling Exchange Web Services.
  • Update your settings: Build your custom allow list and set EWSEnabled=True before the end of August.
  • Coordinate Teams changes: Update your EWS allow list for the upcoming Teams mobile calendar update.
  • Migrate your apps: Plan your complete migration to Microsoft Graph before the permanent shutdown in 2027.

Are you unsure which applications in your tenant still run on legacy systems? Our team can inventory your footprint and sequence your migration before the window closes.

Graphic with text: Exchange Web Services retires — lock in your allow list before October 1. Simple SharePoint, a division of Rego Consulting.

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