Microsoft will deny outdated mobile devices access to Exchange Online. This is necessary to guarantee the service’s security.
From March 1, 2026, mobile devices with an outdated version of Exchange ActiveSync (EAS) will no longer be able to connect to Exchange Online. Only devices using EAS version 16.1 or higher will retain access. Microsoft is taking this step to guarantee the reliability and security of the Exchange Online environment.
The change affects mobile devices that connect to Exchange Online via native email apps, such as the standard Mail app on iOS, Gmail, and Samsung Mail. Microsoft points out that devices using Outlook Mobile are not affected, as this app does not work via the ActiveSync protocol.
Updates available
Microsoft worked with various mobile device and app vendors on this change. The goal is to give users enough time to migrate to recent versions. For example, the iOS Mail app has supported EAS 16.1 since iOS 10. Gmail and Samsung Mail are in the process of rolling out support for EAS 16.1 in their apps.
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In principle, the adjustment should have little impact on users of devices with up-to-date software. For older devices for which updates may not be available, the end of support for older AES versions may have an impact. The question then is to what extent it is responsible to continue working with such outdated devices in a business context.
The measure applies exclusively to Exchange Online and has no impact on Exchange Server. Organizations that need support with the transition are advised to contact their device or software supplier.
Check and migrate
Administrators can check which devices in their organization are still using an older EAS version via a PowerShell command. This generates a report with user names, devices, and associated EAS versions. Microsoft recommends doing this as soon as possible to implement the necessary updates in a timely manner. The following command helps with this:
Get-MobileDevice | Where-Object {($_.ClientType -eq ‘EAS’ -or $_.ClientType -match ‘ActiveSync’) -and $_.ClientVersion -and ([version]$_.ClientVersion -lt [version]’16.1′)} | Sort-Object UserDisplayName | Select-Object UserDisplayName, UserPrincipalName, DeviceId, DeviceModel