Microsoft has announced a significant update to its device connectivity policies for Exchange Online, aimed at enhancing security and ensuring users are on modern protocols.
Starting March 1, 2026, mobile devices running Exchange ActiveSync (EAS) versions older than 16.1 will no longer be able to connect to Exchange Online mailboxes.
Exchange ActiveSync version 16.1 was originally released in June 2016 as part of Exchange Server and Exchange Online updates.
After nearly a decade, Microsoft is phasing out support for older versions to maintain a secure and reliable environment.
This move ensures that all connected devices benefit from the stability and security improvements inherent in the modern protocol.
Microsoft stated that this decision follows extensive collaboration with device and application vendors to minimize service disruptions.
The company emphasizes that if users keep their devices and applications updated to the latest versions, they should experience no interruption in their email service.
This policy change applies specifically to Exchange Online users. It does not affect on-premises Exchange Server environments.
The restriction targets mobile devices using native email applications that rely on the EAS protocol. Common examples include:
- iOS Mail App:Â Users running iOS 10 or later are safe, as EAS 16.1 was adopted with that operating system.
- Gmail & Samsung Mail Apps:Â Microsoft notes that updates for these applications are currently in progress. Users simply need to keep their apps updated to ensure they automatically switch to version 16.1 before the deadline.
IT administrators are encouraged to proactively identify outdated devices within their organization.
Microsoft has provided a PowerShell command that allows admins to generate a report of all devices and applications currently using ActiveSync versions below 16.1.
By running the following command, admins can pinpoint affected users:
powershellGet-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 advised to notify affected users well before the March 2026 cutoff to ensure they update their device firmware or email applications.
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