Changes to Exchange Web Services (EWS) in Exchange Online

Microsoft is phasing out Exchange Web Services (EWS) in Exchange Online. This change affects students at TU Wien with an Exchange Online mailbox.

What’s changing?
Microsoft has begun the phased deactivation of EWS in Exchange Online. As of April 1, 2027, EWS will be completely deactivated in Exchange Online.

Some email programs and applications still use EWS to access Exchange Online. Whether action is required therefore depends on the client you are using.

What does this mean for the email clients you use?

Outlook
You can use a current version of Outlook for Exchange Online. Legacy Outlook for Mac uses EWS for Exchange Online and is therefore not a long-term alternative. Microsoft recommends switching to the latest version of Outlook for Mac.

Thunderbird
Thunderbird supports Microsoft Graph for Exchange Online accounts starting with version 154. Mozilla currently recommends Thunderbird 157 or later. Existing EWS accounts must be set up as new accounts using the Microsoft Graph API. Graph support currently includes email; calendar and address book support are expected to follow later.

Apple Mail and other Apple applications on macOS
Apple Mail, as well as Calendar, Contacts, Notes, and Reminders, currently still use EWS for Exchange Online on macOS. Apple is working with Microsoft to migrate these applications to Microsoft Graph in a future update to macOS 27.

TU Wien has already set up the temporary EWS authorization described by Apple for Apple Internet Accounts. This allows these applications to continue to be used during the transition phase. Apple also confirms the App ID we are using for this temporary solution.

If the TU Wien Exchange account still does not function properly on macOS, we recommend removing the account under System Preferences → Internet Accounts and then adding it again as an Exchange account.

What alternatives are available?
Depending on the desired feature set, the following options are available, for example: The available features may vary depending on the alternative email client. Thunderbird, for example, currently supports Exchange/Microsoft Graph for email, while calendar and address book support are scheduled to follow later, according to Mozilla.

What’s next?
The current EWS release is a transitional solution. Starting April 1, 2027, EWS will be completely disabled in Exchange Online. Applications that still rely on EWS until then will no longer be able to access Exchange Online via EWS.

Since support for various email clients is currently evolving, we provide up-to-date information, known limitations, and notes on individual clients on our information page.

Additional information: 

If you have problems accessing your student mailbox, the Campus IT Service Center will be happy to assist you.

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