Retirement of EWS API by Microsoft - what does that mean for connecting estos applications to Microsoft online services?

When is the final date for the retirement? When will Microsoft deactivate EWS API?

Microsoft will gradually phase out the Exchange Web Services (EWS) API in Exchange Online  from October 2026 and is expected to be fully phased out by the beginning of  April 2027 completely discontinued.

Source: Microsoft announcement... https://devblogs.microsoft.com/microsoft365dev/retirement-of-exchange-web-services-in-exchange-online/

What does the retirement mean?

The EWS (Exchange Web Services) API will then no longer be accessible online: EWS-connected applications will no longer be able to retrieve information (e.g. appointments, contacts, mailbox items) from Microsoft Cloud Services via this API. 

• Affected: Microsoft Cloud Services Exchange Online/Office 365
• Not affected: Self-hosted/local Microsoft Exchange servers (on-premises)

Block access to Exchange Web Services

Deactivation will initially take place via the EWSEnabled  property, which Microsoft will set to false set by Microsoft in October 2026.

This can be changed – i.e. the block can be disabled – via  PowerShell  or, presumably, in the Microsoft 365 admin center (block access to Exchange Web Services).

Our tests have so far revealed the following:

EWSEnabled = null → The EWS connection from ProCall Desktop for Windows works  

EWSEnabled = true and whitelist with the ProCall app → The EWS connection for ProCall Desktop for Windows does not work  

EWSEnabled = true and blacklist without the ProCall app → EWS integration with ProCall Desktop for Windows works  

MetaDirectory 

The Microsoft Graph Import Replicator has been available since MetaDirectory version 5.0.12. It can be used instead of the Microsoft EWS Replicator to connect Microsoft Office 365 / Exchange Online.

Further information: https://support.estos.de/en/metadirectory-enterprise/replikation-von-microsoft-office-365-ews-online

ProCall Enterprise, ProCall Infinity & ProCall NEX

The retirement of the EWS API affects the Microsoft Outlook connection to workstations via EWS in ProCall and thus access to contacts, calendars and appointments.

Contact information can alternatively be retrieved via MetaDirectory.

We are working on a solution to ensure that ProCall can continue to retrieve necessary information (appointments, contacts) from Microsoft Exchange Online / Office 365 even after Microsoft has discontinued the EWS interface.

Further information will be provided in the release notes as soon as it becomes available.

Note on MAPI connection

The MAPI interface is not affected by the deactivation of the EWS interface. In many environments, the connection via Microsoft Outlook (classic Outlook client/MAPI client protocols) can continue to function.