Migrate PST to Outlook: Open & Export Wizard Walkthrough

Importing a PST into Outlook desktop is the closest thing to a stock-standard email task that exists. The Open & Export wizard has been in roughly the same shape since Outlook 2007. That doesn't mean it's foolproof. The places it goes wrong are predictable: profile mismatch, OST cache thrashing during large imports, conflicts with existing folders of the same name, and Exchange Online sync delays that confuse users into thinking the import failed. This walkthrough goes step by step and calls out the failure modes that produce support tickets.

What "PST to Outlook" actually means#

The phrasing is a little loose. Two practical scenarios sit under that label:

• Add the PST as an open data file — Outlook attaches the PST as a separate node in the folder list. Messages stay in the PST, on disk, and never reach Exchange. Useful for browsing an archive without polluting the live mailbox.
• Import the PST into the live mailbox — Outlook reads messages from the PST and writes them into the user's primary mailbox (Exchange Online, Exchange on-prem, or an existing PST). Content syncs to the server if it's an Exchange mailbox.

This guide covers the second one because it's what people usually mean by "migrate." The first is a one-liner: File > Open & Export > Open Outlook Data File. Done.

Prerequisites#

Locate the source PST#

Common PST homes on Windows:

• C:\Users\<user>\Documents\Outlook Files\
• C:\Users\<user>\AppData\Local\Microsoft\Outlook\
• Network shares (\\server\users\<user>\archive.pst)
• USB drives or external SSDs from previous machines
• OneDrive folders, which causes locking issues during import

Copy the PST to a local SSD before starting. Network shares slow the import by an order of magnitude and risk locking conflicts. OneDrive-synced folders are even worse because OneDrive locks the file while syncing and Outlook fights it.

Check file integrity#

Run the Inbox Repair Tool:

"C:\Program Files\Microsoft Office\root\Office16\scanpst.exe"

Newer Office installations also place scanpst at:

"C:\Program Files (x86)\Microsoft Office\root\Office16\scanpst.exe"

Point it at the local copy. If scanpst finds errors, let it repair. Keep the .bak file it generates until the import is complete and verified. A PST that fails scanpst usually fails import at some unpredictable point, leaving partial content behind.

Decide on conversion#

PST to Outlook is the one combination where no conversion is needed. Outlook on Windows reads PST natively. The wizard handles everything from Outlook 97 PSTs through current ANSI and Unicode formats.

The exception is Outlook for Mac. New Outlook for Mac (the rewritten version Microsoft shipped in 2024) supports PST import. Classic Outlook for Mac does not. If you're on classic Outlook for Mac, either upgrade to New Outlook, do the import on a Windows machine, or convert PST to OLM with a third-party tool.

Confirm the target profile#

Outlook must be running with the profile for the destination mailbox. If a user has multiple profiles (one for work, one for personal), launch Outlook with the right one. Otherwise you'll import a PST into the wrong mailbox and have to clean up.

To verify: in Outlook, go to File > Account Settings > Account Settings and check the listed account is the one you intend to import into.

Run the import#

1. Open the wizard

   In Outlook, click File in the top-left ribbon. Choose Open & Export, then Import/Export. The wizard opens.

   If you're on a build where the menu structure is slightly different (the New Outlook on Windows preview), look for Settings > Files > Import. The wizard is the same underneath.

2. Select Import from another program or file

   The first wizard screen lists import types. Select Import from another program or file and click Next.

   Other options on this screen (vCard, iCalendar, CSV) are for different data types. PSTs go through the "another program or file" path.

3. Choose Outlook Data File (.pst)

   The next screen lists file types. Select Outlook Data File (.pst) and click Next.

   If PST is missing from the list, you're on a stripped-down build of Outlook (some Microsoft 365 Business Basic plans). Try a workstation with full Outlook installed.

4. Point to the PST file

   Browse to the local copy of the PST. Outlook also asks how to handle duplicates:

   • Replace duplicates with items imported — overwrites existing messages with PST versions if a duplicate is detected.
   • Allow duplicates to be created — imports everything, may result in double messages if folders overlap.
   • Do not import duplicates — skips messages that already exist in the destination.

   For most migrations, Do not import duplicates is the right choice. It's safe, idempotent if the import is interrupted and restarted, and avoids cluttering folders.

5. Configure destination folder

   The final screen offers two destination options:

   • Import items into the current folder — content lands in the currently selected Outlook folder. Useful for importing one PST folder into a specific destination.
   • Import items into the same folder in — recreates the PST's folder hierarchy inside a chosen account. The dropdown lists accounts; pick the target mailbox.

   For a clean import that doesn't mix archive content with live mail, manually create a top-level folder called Imported Archive in the target mailbox before starting the import, then use "Import items into the current folder" with that folder selected. This keeps imported content separate from live folders.

6. Run the import

   Click Finish. Outlook starts importing. A progress dialog shows the current folder being processed. You can keep using Outlook for other tasks during the import, though it slows responsiveness.

   A 10 GB PST takes 30 to 90 minutes depending on the workstation. The import is CPU-bound and disk-bound. Closing Outlook mid-import is safe; the wizard resumes correctly if you re-run it, though you may end up with partial duplicates if you didn't pick "Do not import duplicates."

7. Wait for Exchange sync if applicable

   If the target is Exchange Online or Exchange on-prem, the imported content lives in the OST cache first and then uploads to the server. Sync time roughly matches import time: 30 to 90 minutes for 10 GB. Monitor sync status in the bottom-right of Outlook (Send/Receive progress).

   Users sometimes panic during this phase because OWA does not show the imported content yet. Set expectations: the messages are there, they're syncing, OWA will catch up.

After the import#

Verify counts#

In Outlook, right-click each imported folder and choose Properties. The total items count appears at the bottom. Compare with the source PST opened in Outlook on the same workstation (use File > Open & Export > Open Outlook Data File to attach the source as a separate node).

Counts should match exactly. If they don't, the wizard logs (%TEMP%\OutlookLogs\) usually identify what was skipped.

Confirm search indexing#

Outlook search uses Windows Search to index OST content. Indexing a freshly imported 10 GB of content takes a few hours. During that time, search results are incomplete. Tell users to wait before assuming missing messages.

To check indexing status: File > Options > Search > Indexing Options. The status row shows how many items remain to index.

Review category and flag preservation#

Outlook flags, categories, and read status all survive PST import because the destination format (OST/Exchange) supports the same metadata. Spot-check a few flagged messages to confirm.

Common failure modes#

Cannot expand the folder. The set of folders cannot be opened.#

The PST is locked by another process. Close Outlook, check Task Manager for outlook.exe processes, kill any lingering ones, then re-run.

The file is not an Outlook data file (.pst)#

Either the file is corrupt or it's an OLM (Outlook for Mac) file with a .pst extension. Run scanpst. If it refuses to open at all, the file might be a renamed OLM; convert it with a Mac-side tool first.

Errors have been detected in the file#

Run scanpst against the file and let it repair. Re-attempt the import after.

Outlook is unable to send or receive items at this time#

The OST is full or the disk is out of space. Free disk on the drive holding the OST, or move the OST to a larger drive.

Authentication failed for the destination account#

Exchange Online OAuth token expired mid-import. Close Outlook, sign back in, and resume the import.

When to skip the wizard#

The Open & Export wizard handles one PST into one Outlook profile. It does not handle:

• Hundreds of PSTs across many user workstations.
• PST to a mailbox that isn't on this workstation's Outlook profile.
• Server-side import without each user's machine being involved.

For those scenarios, the PST to Office 365 network upload route is the right tool — it ingests PSTs server-side from Azure Storage. For PSTs heading to Google Workspace, the PST to Gmail walkthrough covers the IMAP-append flow.

For deeper background on the file formats, see the PST file glossary entry, the OST file glossary entry, and the PST, MBOX, and EML migration guide.