Microsoft to Block Exchange Online Access from Outdated Devices

Microsoft has announced an update to its device connectivity policies for Exchange Online, focusing on enhancing security and ensuring compliance with modern protocols.

Effective from Sun, Mar 1, 2026, mobile devices running Exchange ActiveSync (EAS) versions earlier than 16.1 will be unable to connect to Exchange Online mailboxes. This decision follows the original release of EAS 16.1 in June 2016 as part of Exchange Server and Exchange Online updates.

Microsoft's objective with this policy change is to maintain a secure and reliable environment for all connected devices, leveraging the stability and security improvements of the modern protocol.

This policy update is specific to Exchange Online users and does not affect on-premises Exchange Server environments. The changes primarily impact mobile devices using native email applications that utilize the EAS protocol. Notable examples include:

iOS Mail App: Users running iOS 10 or later are compliant, as EAS 16.1 was included with that operating system. Gmail & Samsung Mail Apps: Updates for these applications are underway. Users should keep their apps updated to transition to version 16.1 before the deadline.

IT administrators are advised to proactively identify outdated devices within their organizations. Microsoft has provided a PowerShell command to generate a report of all devices and applications using ActiveSync versions below 16.1:

Get-MobileDevice -ResultSize Unlimited | Where-Object {($_.ClientType -eq 'EAS' -or $_.ClientType -match 'ActiveSync') -and $_.ClientVersion -and ([version]$_.ClientVersion -lt [version]'16.1')} | Sort-Object UserDisplayName | Select-Object UserDisplayName, Identity, DeviceId, DeviceModel | Format-List

Organizations are encouraged to notify affected users well ahead of the March 2026 cutoff to ensure they update their devices or email applications accordingly.

Based on reporting by GBHackers.