I see a handful of questions each year asking about this file. Sometimes Outlook creates this rogue file and does nothing with it, while some users report that Outlook errors report problems with a file using this extension.
After I upgraded to Office 2010, I noticed an odd file with the extension of .pstst that is not associated with any email account. I deleted the file and Outlook recreated it. How do i get Outlook 2010 to stop creating this file?
This is not a valid file and means the profile is corrupt.
The best fix is a new profile. If you don't want to do make a new profile, you can try editing the registry. Worst case scenario: you'll corrupt the profile even more and need a new profile. In my book, that makes editing the registry a worthwhile risk.
How to edit the registry to remove .pstst
- Press the Windows key + R and type regedit and press Enter to open the registry editor.
- Browse the registry to this key:
HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles\Outlook\9375CFF0413111d3B88A00104B2A6676
- Right-click on the key and choose Export to make a backup.
- Under this key are several subkeys using the name format 0000000x, where x is a number. Each key represents an account, data file, or address book in your profile.
- Look in each key for a value (on the right) named Delivery Store EntryID.
- Double click to open the value and look at the bottom of the dialog for pstst.
- If you use an IMAP account, also check the IMAP Store EID value.
- When you find an entry with the pstst data value, delete the key from the left (0000000x). In my screenshot, this would be the key named 00000006.