Outlook - Transfer PST Files Blocked by OneDrive

Problem

OneDrive does not permit syncing Outlook PST files because of file-type restrictions. When attempting to upload or sync a PST file, you will see the error: This item name or type isn’t allowed.

This article explains a workaround for transferring large PST files (over 20GB) using OneDrive by renaming and compressing the file along with steps to restore and open the PST on a new device.

Solution

Rename and compress the PST file before uploading to OneDrive. OneDrive blocks .pst files but allows .zip files, provided the ZIP name does not indicate it contains a PST.

Prepare the PST file on the old device

1. Locate the PST file.

2. Rename the PST file. Example: jguillotPST-1-27-23.pst > jguillotPST-1-27-23.dat

3. Compress the file into a ZIP.

   1. Right-click the renamed .data file.

   2. Select Send to > Compressed (zipped) folder.

   3. Name the ZIP file something generic (avoid pst). Example: ArchiveBackup.zip

   4. Upload the ZIP file to OneDrive.

Since it’s no longer recognized as a PST, OneDrive will sync it normally.

Download and restore on the new device

1. Download ArchiveBackup.zip from OneDrive.

2. Extract the ZIP file to a local folder.

3. Locate the extracted .data file.

4. Rename it back to a PST. Example: jguillotPST-1-27-23.data > jguillotPST-1-27-23.pst

Place the PST in the correct folder

Do not store the PST in OneDrive, SharePoint, or any synced folder. This will cause corruption and errors.

Move the restored .pst file to: C:\Users\<username>\Documents\Outlook Files\

Open the PST in Outlook

1. Open Outlook.

2. Go to File > Open & Export > Open Outlook Data File.

3. Browse to:

4. Documents > Outlook Files > example.pst

5. Select the file and click Open.

The PST will now appear in Outlook under Outlook Data File, with all folders (Inbox, Sent Items, Archive, etc.).