Microsoft is planning to automatically switch Enterprise users of Microsoft 365 over to the New Outlook for Windows app in April 2026. It already stopped supporting legacy Outlook clients earlier this year.
However, long-time Classic Outlook users have not been the most thrilled about the experience, and that is mainly because they feel the New Outlook app is lacking in terms of feature support. Thankfully, Microsoft is aware of the shortcomings and has already confirmed that it is improving New Outlook operations when an internet connection is unavailable. Multiple new features are being tested, with the latest addition being planned for early 2025.
Aside from better offline mode support, Microsoft is also working on adding PST support on the New Outlook for Windows as well as Outlook for Mac. In fact, the company has already rolled out what it refers to as the "first phase of PST support," and it is described under feature ID 399467 on the Microsoft 365 roadmap. It writes:
Outlook: First phase of PST support in new Outlook for Windows
The first phase PST (a.k.a. Outlook Data File) support in the new Outlook for Windows provides read-only access to Mail items within *.pst files. Users will be able to open *.pst files, read their emails within *.pst files, and search *.pst files for emails. All Calendar, Contacts, and Tasks data saved in the *.pst files are still there, but they cannot be accessed in this preview. Next releases will expand PST support capabilities.
For those wondering, PST or Personal Storage Table is an open proprietary Microsoft file format that is used to import or export Outlook data like email messages, contacts, calendar items, tasks, and notes. The PST files are archived or saved on a user"s PC.
Microsoft also has plans to add PST support on Outlook for Mac since, much like Windows, the feature is currently only supported by the legacy Mac app. This feature was expected to start rolling out in November, but that has not happened.
Under feature ID 405754, the company says:
Outlook: Import and export support for data files in Outlook
This feature adds support for importing PST files into Outlook for Mac. Support for OLM data files will include both importing and exporting data.
Similar to what PST files are for Outlook for Windows, OLM files carry data on Outlook for Mac.
Finally, the latest PST-related addition was made earlier this month under feature ID 473995 and with this, more capabilities are coming to the app. Microsoft writes:
Outlook: Manage email in PST files in new Outlook for Windows
With this update of support for .pst files (a.k.a. Outlook data files) in the new Outlook for Windows, users will be able to move, copy, delete, flag/unflag, mark as read/unread, and set categories for email within .pst files. Additionally, users will be able to create, delete, move, and rename folders within .pst files. Future releases of new Outlook will expand the support for .pst file capabilities.
The rollout of the above is expected in January of next year when a major Microsoft 365 app UI update is also planned.