PST support is beginning to roll out to new Outlook users. Currently the PST files are read-only; you cannot mark the messages read or unread, reply, forward, or delete the messages in the PST. (The feature will be updated in the coming months to support read/write access.) While you can’t copy a message to paste into a new message as an attachment, you can copy the message bodies.
To see if PST support is available in your copy of new Outlook, go to View tab > View Settings > General > Outlook Data Files. It should be available to Microsoft 365 software subscribers who have joined the Insider program for Office. (The Insider program is open to all subscribers. Look for the option on the File > Account page in any Office app. )
Currently, you must have classic Outlook installed to open a PST file in new Outlook. If Outlook was uninstalled by an update, you’ll need to reinstall it if you are using new Outlook and want to open a PST file.
Also, if the filename and display name in classic Outlook is your email address, you may be unable to open it if the same account is in new Outlook. To avoid confusion, I recommend renaming the PST in classic Outlook first.
The ability to open PST files in new Outlook is limited to Microsoft 365 subscribers. You need to either add your Microsoft account to new Outlook or connect your subscription to new Outlook in Settings > Accounts > Your accounts > Add subscription.
If you have a perpetual version of Office, you will not be able to open a PST in new Outlook.
Note: PST files are not supported in the ARM version of new Outlook. This affects some Surface computers and virtual Windows installed on a Mac.
More Information
Microsoft support article: Open and find items in an Outlook Data File (.pst)
