MC1125491 – M365 Change Digest

One-line summary

New Outlook for Windows will let users add file attachments to emails while offline; rollout starts January 2026 for general availability.

Similar updates

Details

RoadmapIds

496371

Summary

Microsoft Outlook for Windows will allow adding file attachments while offline, with rollout starting late October 2025 and completing by February 2026. Users can attach files to drafts offline, which send automatically when reconnected. Admins manage this via the OWAMailboxPolicy-OfflineEnabledWin policy.

Platforms

Desktop

Body (from Message Center)

Updated October 28, 2025: We have updated the timeline. Thank you for your patience.

Introduction

We’re enhancing offline functionality in the new Microsoft Outlook for Windows. This update (Microsoft 365 Roadmap ID 496371) enables users to add file attachments while composing emails offline, improving productivity for those working without an internet connection.

When this will happen

Targeted Release (Worldwide): Rollout begins in late October 2025 and is expected to complete by late November 2025.
General Availability (Worldwide): Rollout begins in early January 2026 (previously mid-December 2025) and is expected to complete by early February 2026 (previously early January 2026).
General Availability (GCC): Rollout begins in mid-February 2026 (previously mid-January 2026) and is expected to complete by late February 2026 (previously late January 2026).

How this affects your organization

Users with offline mode enabled in the new Outlook for Windows will be able to attach files to draft emails while offline. These emails, including attachments, will be sent automatically once the device reconnects to the internet.

This feature will be on or off by default based on your current configuration of the OWAMailboxPolicy-OfflineEnabledWin policy. No changes will be made to existing configurations.

What you can do to prepare

To enable this functionality, ensure the following settings are configured in the new Outlook under Settings > General > Offline:

Enable offline email, calendar, and people
Include file attachments

Admins can manage this feature using the OWAMailboxPolicy-OfflineEnabledWin mailbox policy. Learn more at Set-OwaMailboxPolicy.

Caption i. Offline editing can be enabled or disabled in Settings > General > Offline

Screenshot highlighting toggle to Enable offline email, calendar, and people.

Compliance considerations

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

Raw JSON (for debugging)

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{
  "snapshot_item": {
    "action_required_by": null,
    "ai_action_required_by": "2026-01-01T00:00:00Z",
    "ai_actions": [
      "Review OWAMailboxPolicy-OfflineEnabledWin settings",
      "Enable offline email and attachments in Outlook settings if desired"
    ],
    "ai_master_tags": [],
    "ai_model": "gpt-4.1",
    "ai_summary": "New Outlook for Windows will let users add file attachments to emails while offline; rollout starts January 2026 for general availability.",
    "ai_topics": [
      "Exchange",
      "Microsoft 365 Apps",
      "Outlook"
    ],
    "category": "stayInformed",
    "details_map": {
      "Platforms": "Desktop",
      "RoadmapIds": "496371",
      "Summary": "Microsoft Outlook for Windows will allow adding file attachments while offline, with rollout starting late October 2025 and completing by February 2026. Users can attach files to drafts offline, which send automatically when reconnected. Admins manage this via the OWAMailboxPolicy-OfflineEnabledWin policy."
    },
    "id": "MC1125491",
    "importance": 4,
    "is_major_change": false,
    "last_modified": "2025-10-28T16:29:07Z",
    "ms_products": [
      "Exchange",
      "Microsoft 365 Apps"
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    "platforms": "Desktop",
    "roadmap_ids": [
      "496371"
    ],
    "services": [
      "Exchange Online",
      "Microsoft 365 apps"
    ],
    "severity": "normal",
    "tags": [
      "Updated message",
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    ],
    "title": "(Updated) Microsoft Outlook for Windows: Add attachments while offline"
  }
}