The Exchange team recently announced a phased retirement of Exchange Web Services (EWS) in Exchange Online, with full retirement on April 1, 2027. See Exchange Online EWS, Your Time is Almost Up for the full background.
This change affects hybrid Skype for Business Server deployments, which use EWS today to communicate with Exchange Online. To help administrators prepare, we’ve published a new guide on Microsoft Learn:
Prepare for EWS retirement in Exchange Online
The guide covers what’s changing, the two deadlines that matter, and the exact PowerShell steps to keep Skype for Business Server hybrid functionality working. This post is a short summary — please read the Learn article for the full details.
Who is affected
Only hybrid Skype for Business Server deployments — Skype for Business Server on-premises with user mailboxes in Exchange Online.
Pure on-premises deployments (Skype for Business Server with Exchange Server on-premises) aren’t affected. EWS retirement applies only to Exchange Online.
What you need to do
- Before end of August 2026 — Set EwsEnabled = $true at the tenant level and add the Skype for Business Server App ID and the Skype desktop client App ID to the EWS allowed App IDs list. See Prepare for EWS retirement in Exchange Online for the required App IDs and configuration steps. This keeps Skype for Business Server EWS calls working through the phased disablement and excludes your tenant from the October 1, 2026 auto-switch to EwsEnabled = $false.
- Before April 1, 2027 — Install the upcoming Skype for Business Server update, which replaces EWS calls to Exchange Online with Microsoft Graph API calls. Once installed, Skype for Business Server hybrid will continue to work after EWS is permanently retired.
Detailed steps, PowerShell scripts, and verification commands are in the Learn article: Prepare for EWS retirement in Exchange Online.
Key dates
|
Date |
Event |
|
End of August 2026 |
Deadline to configure EwsEnabled = $true and add the Skype for Business Server and Skype desktop client App IDs to the EWS allowed App IDs list. |
|
October 1, 2026 |
Microsoft auto-sets EwsEnabled = $null → $false for tenants that haven’t opted in. |
|
Before April 1, 2027 |
Install the upcoming Skype for Business Server update (Graph API replacement for EWS). |
|
April 1, 2027 |
Full and permanent EWS retirement in Exchange Online. No exceptions. |
The bottom line
If you run Skype for Business Server hybrid with mailboxes in Exchange Online, start planning now. Both deadlines are firm, and there will be no extensions past April 1, 2027. Read the full guidance in Prepare for EWS retirement in Exchange Online, and watch the Microsoft 365 Message center for the Skype for Business Server update release announcement.
Related reading
- Prepare for EWS retirement in Exchange Online
- Exchange Online EWS, Your Time is Almost Up
- Introducing EWSAllowedAppIDs: Preparing for the Final Phase of EWS Retirement
- Control access to EWS in Exchange
The Skype for Business Server Team
Microsoft