Skype for Business Server Hybrid: Prepare for EWS Retirement in Exchange Online

The Exchange team has recently shared that they will gradually retire Exchange Web Services (EWS) in Exchange Online, with a complete retirement scheduled for April 1, 2027. For more detailed information, check out “Exchange Online EWS: Your Time is Almost Up.”

This transition specifically impacts hybrid deployments of Skype for Business Server, as they rely on EWS for communicating with Exchange Online. To assist administrators in getting ready, we’ve created a new guide on Microsoft Learn:

Prepare for EWS retirement in Exchange Online

The guide explains the upcoming changes, outlines two crucial deadlines, and provides the exact PowerShell commands you’ll need to maintain Skype for Business Server’s hybrid functionality. This post serves as a brief overview; please read the detailed article for more insights.

This change only affects hybrid Skype for Business Server deployments, which mean Skype for Business Server installed on-premises with user mailboxes in Exchange Online. Purely on-premises setups (Skype for Business Server with Exchange Server on-premises) will not be affected. Remember, EWS retirement is applicable only to Exchange Online.

Here’s how you can prepare:

1. Before the end of August 2026 — Enable EWS by setting EwsEnabled to $true at the tenant level. Don’t forget to add the Skype for Business Server App ID and the Skype desktop client App ID to the approved EWS App IDs list. For the needed App IDs and configuration details, refer to Prepare for EWS retirement in Exchange Online. This step ensures that Skype for Business Server’s EWS calls continue to function through the gradual disablement period and prevents your tenant from being automatically switched to EwsEnabled = $false on October 1, 2026.
2. Before April 1, 2027 — Install the upcoming update for Skype for Business Server, which will replace EWS calls to Exchange Online with calls to the Microsoft Graph API. Once this update is installed, your hybrid Skype for Business Server setup will continue working seamlessly after EWS is officially retired.

You can find detailed steps, PowerShell scripts, and verification commands in the Learn article: Prepare for EWS retirement in Exchange Online.

If you manage a hybrid Skype for Business Server setup with mailboxes in Exchange Online, it’s crucial to start your preparations now. Both deadlines are strict, and there will be no extensions beyond April 1, 2027. For complete guidance, please check the full article at Prepare for EWS retirement in Exchange Online, and keep an eye on the Microsoft 365 Message Center for updates about the Skype for Business Server update release.

Best regards,

The Skype for Business Server Team