Outlook: open attachments while offline in the new Outlook for Windows

Originally posted by Microsoft Apr 4, 2025 Uncategorized 0 Comments

We are adding more functionality to offline mode in the newOutlook for Windows. You will now be able to open and save attachments fromyour emails without an internet connection.   

Please note that this is only scoped to classic fileattachments. OneDrive and SharePoint links in the body of the emails will stillneed a connection to be opened.   

For this functionality to work you need to make sure Offlineis enabled and offline attachments are enabled.   

At the user level you can verify this by checking twosettings in new Outlook Settings – General – Offline:   

1. Enable offline email, calendar and people  
2. Include file attachments  

This functionality will also be enabled or disabled based onthe True/False behavior of the already existing Mailbox Policy:OWAMailboxPolicy- OfflineEnabledWin. 

Attachments from emails within the timeframe and folderscope selected in the “Settings – General – Offline” will be syncedand available locally for users to open without an internet connection.  

This message is associated with Microsoft 365 Roadmap ID 472026

When this will happen:

Targeted Release (Worldwide): We will begin rolling out on mid-May 2025 and expect to complete by late May 2025.

General Availability (Worldwide): We will begin rolling out on late June 2025 and expect to complete by mid-July 2025.

General Availability (GCC): We will begin rolling out on mid-July 2025 and expect to complete by late July 2025.

How this will affect your organization:

Classic attachments from emails within the timeframe andfolder scope selected in the “Settings – General – Offline” will besynced and available locally for users to open without an internetconnection:

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What you need to do to prepare:

The default on or off of this feature will depend on yourexisting Offline configuration in the new Outlook via the following policy:OWAMailboxPolicy- OfflineEnabledWin.  This feature willnot change the default of this Policy. You can find more information about this Policy here: Set-OwaMailboxPolicy  

If you have not made any changes to this Policy, then thedefault of this feature will be on. 

Message ID: MC1047925