How to Import a PST File into Outlook
In short: To import a PST into Outlook, go to File → Open & Export → Import/Export, choose Import from another program or file, then pick Outlook Data File (.pst) and browse to your file. This is a classic Outlook feature. New Outlook can now import a PST too but it still needs classic Outlook installed alongside it.
Import a PST step by step (classic Outlook)
The full import wizard lives in classic Outlook. It merges the PST contents into the mailbox you choose.
- Open Outlook and click File at the top-left.
The File tab in Outlook. - Choose Open & Export then click Import/Export.
Open & Export with Import/Export. - Select Import from another program or file then click Next.
The Import and Export wizard. - Pick Outlook Data File (.pst) then click Next.
Choosing the PST file type. - Browse to your
.pstfile, choose how to handle duplicates then click Next.
Selecting the PST file and duplicate handling. - Pick the folder or account to import into then click Finish.
Choosing the destination and finishing.
Technical Executive and Staff Writer, Corbett Software
“The step that trips people up is not the wizard, it is the choice before it. If you only need to read the mail, use Open, not Import. Import merges everything into your live mailbox and undoing that is far more work than opening a PST in its own folder list.”
Open the PST instead, if you only want to read it
If you just need to see the old mail and not merge it in, use Open rather than Import. Go to File → Open & Export → Open Outlook Data File and pick the .pst. It shows up as its own folder list in the sidebar and nothing is copied into your main mailbox.
Importing a PST into New Outlook
New Outlook started as a cloud-first app with no PST support at all. Microsoft added PST import in March 2026, so it is possible now, but there are conditions that trip a lot of people up. Microsoft’s own support notes confirm classic Outlook has to be installed for New Outlook to bring in a PST.
- Classic Outlook has to be installed on the same PC.
- Both versions must be the same architecture, either 32-bit or 64-bit.
- The account signed into New Outlook needs a Microsoft 365 subscription. Without one you see the message Outlook Data Files require a Microsoft 365 Subscription.
- It is not available on the ARM build of New Outlook.
If any of that is in your way, the simplest path is to switch to classic Outlook with the top-right toggle, run the import there then switch back. The mail syncs to both views.
Import/Export is greyed out or missing
If the Import/Export option is greyed out or the whole File menu is missing, you are almost certainly in New Outlook or a web version rather than the classic desktop app. Switch to classic Outlook first. The full walkthrough is here: fix a greyed-out Import/Export menu.
Outlook says “this is not an Outlook data file”
This error usually means the PST is an old ANSI file or it is damaged. Modern Outlook expects the Unicode format. If the file is corrupt, repair it before importing: see repair a PST file without ScanPST. More on this exact error: Outlook says this is not an Outlook data file.
Is there a size limit for importing a PST?
A PST (Outlook Data File) is a single file that holds your mail, contacts and calendar. Its size does have a ceiling. A modern Unicode PST holds up to 50 GB by default, which is what Outlook 2016, 2019, 2021 and Microsoft 365 create. Very old ANSI PST files, made before Outlook 2003, stop at 2 GB. Anything over about 20 GB imports slowly and is more likely to error, so it is worth splitting or converting a large file first.
Importing a password-protected PST
A password on a PST does not stop the import. When you browse to the file, Outlook asks for the password before it reads the data. Type it in and the import runs as normal. If you have lost the password, Outlook cannot recover it for you and you will need a separate recovery tool.
Sometimes you do not want to import at all. If you need to open a PST without Outlook, pull it into another format or split a huge file before importing, a dedicated tool does the job. The Corbett PST File Converter reads a PST directly with no Outlook profile needed and exports it to PDF, MBOX, EML or CSV while keeping the folder structure. A free demo edition lets you check the result first. It runs on every edition of Windows.
Frequently asked questions
Where does Outlook import the PST to?
Into the folder or account you choose on the last screen of the wizard. Pick your main mailbox to merge the mail in or create a fresh folder to keep the imported items separate.
Can I import a PST into New Outlook without classic Outlook?
Not yet. As of 2026 the New Outlook PST import still needs classic Outlook installed on the same machine. Microsoft has said it plans to drop that requirement, but for now classic Outlook is the reliable route.
Does importing a PST duplicate my emails?
It can, if the same mail already exists in the target mailbox. The wizard lets you choose to replace duplicates, allow duplicates or not import duplicates, so pick the option that matches what you want.
How do I open a PST without Outlook?
You do not need Outlook to read a PST. A PST viewer or converter opens the file on its own and shows the mail, so you can browse or export it without an Outlook profile.
Can I open a PST file on Mac or Linux?
Not in Outlook, because there is no classic Outlook for Mac or Linux that imports a PST. A cross-platform PST viewer or converter can open the file. You can also convert the PST to a format your mail app on that system reads.
What is the largest PST Outlook can import?
A Unicode PST is capped at 50 GB by default. You can raise that limit through the Windows registry, but a file that large is slow and fragile, so splitting it first is usually the better move.
Can I import an OST the same way?
No. Outlook will not import an OST directly. You have to convert it to a PST first. The steps are here: import an OST file into Outlook.
