Microsoft 365 Message Center item MC1125491
MC1125491 - (Updated) Microsoft Outlook for Windows: Add attachments while offline
Microsoft Outlook for Windows now allows adding file attachments to emails while offline. Rollout began in late October 2025 for Targeted Release and is generally available worldwide. Users can enable offline email and attachments in settings; emails with attachments send automatically once online. Admins manage via OWAMailboxPolicy-OfflineEnabledWin.
- Message Center ID
- MC1125491
- Category
- stay Informed
- Severity
- normal
- Services
- Exchange Online, Microsoft 365 apps
- Tags
- Updated message, New feature
- Roadmap ID
- 496371
- Platforms
- Desktop
- Published
- 2025-07-30
- Last updated
- 2026-06-05
- Expires
- 2026-07-31
Updated June 5, 2026: We have updated the timeline. Thank you for your patience. IntroductionWe’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 March 2026 (previously late November 2025). General Availability (Worldwide): This is now currently available.General Availability (GCC): Rollout begins in early June 2026 (previously early May) and is expected to complete by end of June 2026 (previously late May).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 attachmentsAdmins 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 > OfflineCompliance considerations No compliance considerations identified, review as appropriate for your organization.