New Microsoft Outlook for Windows: Offline support for mail actions and compose

Updated July 22, 2024. We have added a link to an article that has more details about the feature.

The first set of offline capabilities in the new Microsoft Outlook for Windows will be rolling out worldwide in the coming months. Mail, calendar events, and contacts will be saved on the user’s device, so those items can be viewed even when not connected to the internet. Additionally, key actions can be performed on emails, including flag, move, and delete, and new emails can be composed, saved, and sent, so users can stay productive even when not connected to the internet.

This message is associated with Microsoft 365 Roadmap ID: 178030.

When this will happen:

General Availability (Worldwide): We will begin rolling out in late June 2024 and expect to be complete by late July 2024.

How this will affect your organization:

Before the rollout: New Outlook had no offline capabilities.

After the rollout

Features: Users will have the ability to view mail, calendar events, and contacts in the new Outlook for Windows when not connected to the internet. After a user connects to the internet, actions performed on emails while offline will synchronize back to the server and emails sent while offline will complete sending, moving from the Outbox to Sent Items.

Improved performance: By saving items on the user’s device, the performance of the new Outlook will be improved, because interacting with items saved on the device is faster than interacting with items loaded via a network connection.

Storage impact: Because items are saved on the user’s device, the new Outlook will require more local storage on the user’s device. The storage impact will depend on which folders are saved, how many items are saved, and size of the individual items.

Settings: Users can adjust the folders to save, adjust the number of days of email and calendar events to save, and turn off the feature in new Outlook for Windows > Settings > General > Offline. The feature is enabled by default with these settings:

1. Folders to save: Inbox, Sent Items, Drafts, Archive, Deleted Items, Snoozed, and Favorites (can be changed to exclude Favorites or include recent folders)
2. Days of email to save: 7 days (can be increased up to 180 days)
3. Days of calendar events to save: 30 days (in the past and future) (can be increased up to 180 days)

Features that are not supported when not connected to the internet will display error messages.

Future capabilities: Additional capabilities will be available later in 2024.

Default offline settings in the new Outlook for Windows:

What you need to do to prepare:

No action is required to prepare for this rollout. You may want to notify your users about this change and update any relevant documentation as appropriate.

If you would like to disable this feature, set the new Exchange PowerShell -OwaMailboxPolicy cmdlet parameter OfflineEnabledWin to False. When disabled, no items will be saved on the user’s device, which also means users will not receive the performance improvements described in this message. Any items saved prior to disabling the feature will be deleted.

To use OfflineEnabledWin, the mailbox account must be the primary account in the new Outlook. To prevent end users from changing the primary account, set the parameter ChangeSettingsAccountEnabled to False.

Note: Another parameter, OfflineEnabledWeb, will be available when offline capabilities for Outlook on the web are rolled out (separate from this rollout, and not yet planned).

Learn more: The -OfflineEnabledWin section in Set-OwaMailboxPolicy (ExchangePowerShell) | Microsoft Learn

Before rollout, we will update this post with revised documentation.

We have published this article with more details about the feature: Switch from working offline to online - Microsoft Support