EWS Migration

Exchange Web Services (EWS) is a technology that was developed specifically for accessing Exchange data. The API enables access to data from Microsoft Exchange Server and Exchange Online, including emails and mailboxes. EWS has been a central interface for third-party solutions such as archiving systems.

Microsoft is discontinuing Exchange Web Services (EWS) for Microsoft 365

Microsoft has announced that it will block access to Exchange Web Services (EWS) for Exchange Online starting October 1, 2026. EWS will be completely shut down by April 2027. This decision affects all organizations that use EWS in conjunction with Exchange Online (Microsoft 365). After the shutdown, some resources will only be accessible via the Graph API, while for other resources there is currently no Graph API equivalent. These resources will then no longer be accessible by third-party solutions.

Microsoft will preconfigure and potentially restrict access to EWS based on usage starting in August 2026. Administrators can also manage the settings themselves.

For customers using Exchange Online Kiosk, Microsoft Office 365, and Office 365 F1/F3, Microsoft will disable EWS access as early as June 2026.

What will change for MailStore Server and MailStore SPE?

The shutdown of EWS initiated by Microsoft will require adjustments in MailStore Server and MailStore SPE, depending on the archiving strategy. Archiving methods within MailStore Server and MailStore SPE that previously have used EWS may no longer be able to connect after October 1st and will then encounter errors.

Which protocols does MailStore use?

Up to and including version 25.4, MailStore exclusively created Microsoft 365 archiving and export profiles that used EWS. Starting with version 26.1, new archiving profiles for regular mailboxes use the Graph API. New archiving profiles for archive mailboxes and public folders continue to use EWS, as these are not accessible via the Graph API. New export profiles, starting with version 26.2, use the IMAP protocol, since importing complete emails into a Microsoft 365 mailbox using the Graph API is also not possible.

How can MailStore support me during the migration?

Make sure you have completed the app registration in Entra ID according to our instructions. In particular, the Mail.ReadWrite and IMAP.AccessAsApp permissions are now required.

The summary of archiving profiles contains the protocol used. Microsoft 365 Journal archiving profiles do not typically use EWS and are therefore not affected.

If you have configured Microsoft 365 profiles that can be converted, this message will appear on the dashboard:

Click this message to open the Microsoft 365 Profile Conversion Tool. Use this tool to test and perform a conversion.

When do adjustments need to be made?

June 2026

If you are an Exchange Online Kiosk, Microsoft Office 365, or Office 365 F1/F3 customer, all profiles must be migrated to Graph API and IMAP.

Archiving Exchange Online archive mailboxes and Exchange Online Public Folders will no longer be possible.

October 2026

EWS profiles will continue to function after October 2026 if EWS access in Microsoft 365 is configured accordingly.

April 2027

EWS profiles will no longer function after April 2027. Archiving regular mailboxes using Graph API and exporting to Microsoft 365 using IMAP will continue to function. Archiving Exchange Online archive mailboxes and Exchange Online Public Folders will no longer be possible. Microsoft has hinted at a future solution, but has not yet published a concrete plan. Microsoft recommends migrating public folders to Microsoft 365 Groups.