MC1197103 – M365 Change Digest

One-line summary

Starting March 1, 2026, Exchange Online will block devices using Exchange ActiveSync versions lower than 16.1 to enhance security and reliability.

Similar updates

Details

Summary

Starting March 1, 2026, Exchange Online will block devices using Exchange ActiveSync versions below 16.1 for improved security. Organizations must update mobile devices and apps to EAS 16.1 or higher. Outlook Mobile is unaffected. Admins can identify outdated devices using a provided PowerShell command.

Body (from Message Center)

Updated December 16, 2025: We have updated the PowerShell example. Thank you for your patience.

Exchange Online ActiveSync Device Support Update

We’re making a change to improve security and reliability in Exchange Online. Starting March 1, 2026, devices using Exchange ActiveSync (EAS) versions lower than 16.1 will no longer be able to connect to Exchange Online. EAS 16.1 was introduced in June 2016 and provides enhanced compatibility and security.

When this will happen:

This change begins taking effect on March 1, 2026.

How this affects your organization:

Who is affected: Organizations using mobile devices with native email apps to access Exchange Online mailboxes via EAS protocol. Apple devices added support for EAS 16.1 in iOS 10 and are unlikely to be affected. The Gmail app and Samsung Mail will have updated versions available before the deadline. For other apps you should contact your device or application vendor if they are using EAS versions lower than 16.1.

What will happen:

Devices running EAS versions lower than 16.1 will no longer connect to Exchange Online.
Devices using Outlook Mobile are not impacted because they do not use EAS.
This change applies only to Exchange Online, not Exchange Server.

What you can do to prepare:

Verify that all mobile devices and applications are updated to EAS version 16.1 or higher before March 1, 2026.
Admins can generate a report of devices using older EAS versions with the following PowerShell command:


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

Communicate this change to your helpdesk and end users and ask them to update if possible.
Update internal documentation as needed.
For assistance, contact your device or application vendor.
Learn more: Exchange ActiveSync in Exchange Online

Compliance considerations:

No compliance considerations identified, review as appropriate for your organization.

Raw JSON (for debugging)

Expand/collapse the full payload below.

Show/hide raw

{
  "snapshot_item": {
    "action_required_by": "2026-02-28T08:00:00Z",
    "ai_action_required_by": null,
    "ai_actions": [
      "Identify devices using EAS below 16.1",
      "Update affected devices/apps to EAS 16.1+",
      "Notify helpdesk and users",
      "Update internal documentation"
    ],
    "ai_master_tags": [
      "Security"
    ],
    "ai_model": "gpt-4.1",
    "ai_summary": "Starting March 1, 2026, Exchange Online will block devices using Exchange ActiveSync versions lower than 16.1 to enhance security and reliability.",
    "ai_topics": [
      "Exchange"
    ],
    "category": "planForChange",
    "details_map": {
      "Summary": "Starting March 1, 2026, Exchange Online will block devices using Exchange ActiveSync versions below 16.1 for improved security. Organizations must update mobile devices and apps to EAS 16.1 or higher. Outlook Mobile is unaffected. Admins can identify outdated devices using a provided PowerShell command."
    },
    "id": "MC1197103",
    "importance": 5,
    "is_major_change": true,
    "last_modified": "2025-12-16T20:24:38Z",
    "ms_products": [
      "Exchange"
    ],
    "platforms": null,
    "roadmap_ids": [],
    "services": [
      "Exchange Online"
    ],
    "severity": "normal",
    "tags": [
      "User impact",
      "Admin impact",
      "Retirement"
    ],
    "title": "(Updated) Exchange Online ActiveSync device support update"
  }
}