Import a PST into Outlook

Before you start

• Copy the PST to a local drive, for example Documents\Outlook Files. Outlook doesn’t support PST files on network shares, and a PST inside a OneDrive, Dropbox or iCloud synced folder can be corrupted while Outlook has it open.
• Open or import? Opening a PST adds it to the folder pane as a separate data file; nothing is copied, and it stays on this computer. Importing copies the messages into your mailbox. With a Microsoft 365, Outlook.com or Exchange account, they are then uploaded to the server and appear on all your devices.
• Large PST files take a while: importing several gigabytes can take an hour or more, and a server mailbox then needs time to sync.

Classic Outlook for Windows (Microsoft 365, 2021, 2019, 2016)

Import into your mailbox

1. Click File → Open & Export → Import/Export.
2. Choose Import from another program or file and click Next.
3. Choose Outlook Data File (.pst) and click Next.
4. Click Browse and select your PST. Under Options, pick Do not import duplicates (recommended if you might import twice), then click Next.
5. Select the top folder (the PST name, for example “Imported Mail”) and keep Include subfolders ticked.
6. Choose where the mail goes. Import items into the same folder in merges Inbox with your Inbox, Sent Items with your Sent Items, and so on. To keep the old mail apart, import into the current folder after creating a new folder like Old mail and selecting it.
7. Click Finish and wait for the progress window to close.

Just open the PST

1. Click File → Open & Export → Open Outlook Data File.
2. Select the PST and click OK. It appears at the bottom of the folder pane.
3. To remove it later, right-click its name → Close “Imported Mail”. The file itself stays on disk.

New Outlook for Windows

The new Outlook (the default app on new Windows 11 PCs) gained PST support in stages through 2025 and 2026. As of November 2026 it needs classic Outlook installed on the same PC (same 32- or 64-bit version) to read PST files. In current builds:

1. To import a PST into an account, open Settings → Files (called Data files in some builds) and choose Import.
2. To open a PST as a separate data file instead, go to Settings → Files → Outlook Data Files and choose Add file.
3. Select the PST and follow the prompts to choose the destination account and folders.

Outlook for Mac

1. In Outlook, choose File → Import (in some versions Tools → Import).
2. Select Outlook for Windows archive file (.pst) and click Continue.
3. Choose your PST and click Import. When it finishes, click Done.
4. The imported folders appear under On My Computer in the sidebar. To copy them to your mail account so they sync, drag the folders or messages onto that account.

Microsoft 365, Outlook.com and Exchange mailboxes

• Mailbox quota: importing into a server mailbox counts against its storage. Check your quota (in Outlook on the web: Settings → General → Storage) before importing a large PST, or open the PST as a separate data file instead.
• Many mailboxes or very large files: Microsoft 365 administrators can use the PST Import Service (in Microsoft Purview) to upload PST files to Azure and import them into mailboxes on the server, without going through each user’s Outlook.
• Outlook may look done before the server has caught up. Leave Outlook open and connected until the folder counts stop changing.

Large PST files

We create PSTs in the modern Unicode format, which Outlook 2010 and later open. By default, Outlook limits a Unicode PST to 50 GB. Administrators can raise this limit with the MaxLargeFileSize and WarnLargeFileSize registry settings, but large PSTs are slower to work with. For very large archives, consider splitting your mail into several conversions, for example one per account or per year.

Troubleshooting

• “The file is in use” or “cannot be accessed”: make sure the PST isn’t open in another program or still downloading, and that it’s on a local drive.
• Folders look empty: click the folder and wait a moment; Outlook builds its views the first time a PST is opened. Also check that Include subfolders was ticked.
• Still stuck? Contact us with your conversion ID and we’ll help.