Dear colleagues, 

Microsoft is making a security and reliability update to Exchange Online that may affect a number of older mobile devices used to access U of T email. 

What is changing 

Starting March 1, 2026, Microsoft will no longer allow connections to Exchange Online from devices using very old versions of Exchange ActiveSync (EAS). Exchange ActiveSync is the technology used by some built-in mobile mail apps to sync email, calendar, and contacts. 

Devices and apps that use Exchange ActiveSync version 16.1 or higher will continue to work normally. 

Who is affected 

We have sent targeted communications to the impacted users. 

This change only affects mobile mail apps that use an older connection method. It does not affect email on computers or the Outlook mobile app. 

Most modern devices and apps already support the required version and are not expected to be impacted. The Outlook mobile app is not affected by this change. 

Timeline 

• • Now to February 28, 2026. Users should update devices and apps as needed. 

• • March 1, 2026. Connections from unsupported Exchange ActiveSync versions will be blocked by Microsoft. 

Resources 

• • Exchange ActiveSync in Exchange Online. Microsoft Learn. 

• • Outlook for iOS and Android. Microsoft Learn. 

If you have any further questions or concerns, please submit a ticket to the Enterprise Service Centre at (https://uoft.me/m365help). 

Kind regards, 

Enterprise Applications & Solutions Integration (EASI)
Information Technology Services, University of Toronto