Transfer Outlook PST Files to a New PC

Classic Outlook keeps a local copy of your data in two kinds of files. The OST file (offline Outlook Data File) is a synchronized copy of your mailbox, used by Microsoft 365, Exchange, Outlook.com and IMAP accounts. Microsoft states that you do not need to back it up: when you set up the account on another computer, Outlook creates a new file and downloads your messages again from the server.

A PST file (Outlook Data File), on the other hand, holds the only copy of its items. That is the case for POP accounts, which download messages from the server to the PC, and also for archives (archive.pst), PST files you created yourself and exports. In earlier versions of Outlook, IMAP accounts also used a PST; recent versions give them an OST.

To check your account types, open File > Account Settings > Account Settings in Outlook: the type of each account is shown there. A single profile can mix both cases, for example a Microsoft 365 account plus a PST archive.

By default, Outlook saves PST files in C:\Users\<user>\Documents\Outlook Files. Older versions used C:\Users\<user>\AppData\Local\Microsoft\Outlook, a hidden folder that also holds the OST files. A PST file may still sit somewhere else, even on another drive: ask Outlook for the exact list.

1. In Outlook, open File > Account Settings > Account Settings.
2. Select the Data Files tab: it lists every PST and OST file in the profile with its location.
3. Select a PST file, then Open File Location to show its folder in File Explorer.

If your Documents folder syncs with OneDrive, Microsoft warns that a large PST file can slow down syncing. For the transfer itself, an external drive or USB stick is a better choice.

A manual transfer has two parts: copy the PST files to external storage, then attach them to Outlook on the new PC. Copying a PST file does not carry over your email account settings, so the account has to be set up again.

1. On the old PC, close Outlook and wait until it has fully exited: while it runs, it keeps the PST files open.
2. Copy each PST file you located in the previous step to an external drive or USB stick.
3. On the new PC, install classic Outlook and add your email account.
4. Copy the PST files to a local folder, for example Documents\Outlook Files.
5. To attach a PST file as it is (archive, POP account), choose File > Open & Export > Open Outlook Data File, then select the file: its folder tree appears in the navigation pane.
6. To merge its contents into a mailbox instead, choose File > Open & Export > Import/Export, then Import from another program or file and Outlook Data File (.pst). Pick the file, how to handle duplicates and the destination folder, then Finish.

If the PST file is password-protected, Outlook asks for the password whether you open or import it.

A PST file holds your messages with their attachments, contacts, calendar and tasks. However, Microsoft states that Outlook does not export folder properties (views, permissions, AutoArchive settings), message rules or blocked senders lists to a PST, so importing a PST does not bring them back. Other settings are stored in separate files in your Windows profile.

• Rules: before leaving the old PC, open File > Manage Rules & Alerts > Options > Export Rules to get an .rwz file, then use Import Rules on the new PC. This feature exists only in classic Outlook.
• Blocked senders and folder views: note your settings so you can recreate them on the new PC.
• Signatures: they are stored in C:\Users\<user>\AppData\Roaming\Microsoft\Signatures. Copy the contents of this folder to the same location on the new PC.
• AutoComplete: for Microsoft 365, Exchange and IMAP accounts, the list of suggested addresses is a hidden message in the mailbox, which Microsoft suggests copying with the MFCMAPI tool; for a POP account, it is an .nk2 file you import with the outlook /importnk2 command. With Exchange Online and a recent version of Outlook for Microsoft 365, suggestions come from Microsoft Search: there is nothing to copy.
• Other settings: message templates (.oft), your custom dictionary and print styles sit in subfolders of AppData\Roaming\Microsoft.

UserNest backs up a Windows user profile to a folder (external drive, USB stick or any folder you choose), then restores it on the new PC. For classic Outlook, from Outlook 2010 to Microsoft 365 including 2013, 2016, 2019 and 2021, it covers PST files, Outlook profiles stored in the registry, signatures and AutoComplete (NK2 files and the RoamCache folder). OST files can be included, but their box is unchecked by default because Outlook rebuilds them.

1. On the old PC, start UserNest, check Outlook and the other items you want to move, then click Analyze to estimate the size of the backup.
2. Run the backup to the external drive. If Outlook is open, UserNest lists it and closes it once you confirm, so that the files are copied in a consistent state.
3. On the new PC, install classic Outlook: UserNest does not transfer applications or their licenses.
4. Restore the backup, which is stored on the drive in a folder named user@PC. PST files return to the same relative location in the new profile, or to the same folder if the original drive exists.
5. UserNest re-imports the Outlook profile and updates its PST and OST paths automatically, so you do not have to reopen each data file by hand.
6. Check the final report: it shows "Done" or "Completed with errors", with access to the detailed log.

As a precaution, also export your rules to an .rwz file as described above. On first launch, Outlook may ask for your account passwords again. The Consumer version installs from the Microsoft Store (Download UserNest); to migrate several machines, the Pro version is a portable executable that runs from a USB stick. License terms are on the Pricing page.

The new Outlook for Windows is not affected by this kind of transfer: its data is in the cloud and comes back when you sign in to your account on the new PC. That is why UserNest does not handle it. To tell which version you use, look at the top bar: if you only see the Outlook icon, you are on classic Outlook; if the product name appears next to it, you are on the new Outlook. The Send / Receive tab exists only in classic Outlook.

Keeping PST archives? According to Microsoft, PST support in the new Outlook is still partial: opening a PST file there requires, among other things, classic Outlook to be installed too and a Microsoft 365 subscription. Check these requirements before you part with the old PC, or keep classic Outlook to browse your archives.