Microsoft EWS to Graph Migration October 2026

Earlier this year, Microsoft announced that they would begin a phased shutdown of EWS on Microsoft 365/Exchange Online starting in October of 2026 with the goal of a complete shutdown in 2027. If you are currently using Thunderbird’s EWS support to connect to a Microsoft 365/Exchange Online email account, then you will need to switch to the Microsoft Graph API support to keep using Thunderbird beyond these dates. Microsoft Graph support is available in Thunderbird versions 154 and higher.

Thunderbird does not support migrating accounts to different protocols. Instead, you will need to set up a new account. If you have an existing EWS-connected Microsoft 365 account, first you’ll need to delete that account in Thunderbird. You can do this from Thunderbird app menu ☰ > Account Settings > click on your EWS account in the left sidebar > Delete.

Deleting the account locally in Thunderbird will not affect any data stored on Microsoft 365, so your data is safe.

Once your previous EWS account has been deleted, you can use Account Hub to set up a new account. In Thunderbird app menu ☰ > Add Account > Email enter your Microsoft 365 hosted email account. Thunderbird should automatically detect that your email is hosted on Microsoft 365 and will give you a few options for getting connected. Click the Microsoft Graph API button when presented with the list of available protocols.