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Microsoft has confirmed that New Outlook on Windows is closing the feature gap with Outlook Classic, specifically regarding advanced Personal Storage Table (.PST) file handling. The company also addressed long-standing issues with delegated mailboxes and added user control over calendar notification blasts.
While .PST support was introduced in New Outlook earlier this year, it was initially limited to basic read-only access or simple exports. Microsoft has now fully released advanced capabilities, allowing users to import emails, calendars, and contacts directly from PST files into their active mailbox. This marks the final phase of a multi-month rollout that began in June 2025.
Advanced .PST support is live (with a catch)
You can now open, search, and import data from .PST files within New Outlook without losing functionality. To use this feature, navigate to Settings, select Data files, and choose Add files to locate your PST.
However, there is a significant dependency: Outlook Classic must still be installed on your system for this to work. Microsoft’s support documentation clarifies that both New Outlook and Classic Outlook must share the same architecture—either both 32-bit (x86) or both 64-bit (x64). If you uninstall Classic Outlook, PST functionality will break.
Microsoft has stated it plans to remove this dependency later in 2026. Once the standalone PST support is fully decoupled from Classic Outlook and bulk import features are complete, the company will cease further development of PST-specific features in New Outlook.
Calendar updates no longer blast everyone
A frustrating quirk in New Outlook has been its tendency to automatically send update notifications to all attendees whenever you made minor edits to a meeting, such as changing the description or adding a single person. This often resulted in unnecessary email clutter for participants.
Microsoft has marked this feature development as complete. The upcoming update will introduce a confirmation prompt when editing calendar events. You will now have the choice to Save changes locally without notifying attendees, or explicitly choose to Send Update. This gives you granular control over communication noise.
Delegated mailbox Sent Items bug fixed
Users managing shared or delegated mailboxes have long reported that emails sent from those accounts did not appear in the correct Sent Items folder. Instead, replies sent via a shared address were incorrectly saved to the primary user’s personal Sent Items, leaving the shared mailbox’s history empty.
This behavior differed significantly from Outlook Classic, where sent items were correctly logged in the respective shared folder. Microsoft confirms this issue is being resolved internally and will be fixed in an upcoming release, ensuring that delegated mailbox histories remain accurate and accessible.
What this means for you
If you rely on New Outlook but keep Classic Outlook installed for legacy PST support, you can now transition more of your workflow to the new interface. The ability to import old data directly into your current mailbox simplifies migration from older accounts. Additionally, IT professionals and power users managing shared inboxes will see improved accuracy in email tracking.
Keep an eye on your Windows Update settings or Microsoft Store for the next New Outlook update to access these features. Note that while PST support is advanced, it remains tied to Classic Outlook until the final decoupling later this year.
Source: Windows Latest
Over to you: Will you uninstall Outlook Classic once the PST dependency is removed later this year, or keep it for safety?
