Repairing the Outlook data file: damaged PST or OST, SCANPST and a new OST

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The short answer: Outlook keeps mail in a data file on the computer: an OST (a copy of what is on the server, for recent IMAP and Exchange accounts) or a PST (mail that may exist only there, for POP accounts and archives). When that file gets damaged you see errors like 0x8004010F, empty folders or Outlook closing by itself. An OST is rebuilt; a PST is repaired with Microsoft’s tool.

OST or PST: what changes

File What to do if it is damaged
OST (server copy) Close Outlook, rename it (for example, to .old) and open Outlook: it creates a new one and downloads everything from the server. Nothing is lost if the account is IMAP.
PST (local data) Repair it with the Inbox Repair Tool (SCANPST.EXE). Take a copy of the file first.
You do not know which In File > Account Settings > Data Files you see each file’s name and folder. The extension tells you which.
The file is huge A very large file gets slower and more fragile. Archive old mail or reduce how much stays offline.

How to repair or rebuild

1 Close Outlook and check Task Manager that it is not still running.
2 Find the file: the path is in File > Account Settings > Data Files > Open File Location.
3 Take a copy of the file to another folder before any repair.
4 If it is an OST: rename it (add .old at the end) and open Outlook. It creates a new file and downloads the mail from the server again: with many years of mail, it takes a while.
5 If it is a PST: look for SCANPST.EXE in the Office installation folder (the path changes with the version; Windows search finds it), open it, choose the file and press Start then Repair. Repeat until it finds no errors.
6 Open Outlook and check the folders. Whatever the tool recovered without a proper folder shows up in “Recovered Items” or “Lost and Found”.
A PST from a POP account may be the only copy of your mail. Do not delete it or “rebuild” it as you would an OST: repair it, and keep the copy you took. If you are not sure what it is, ask us before touching it.
To keep it from happening again, use IMAP (mail stays on the server and the OST is just a copy) and do not let the file grow without limit: POP or IMAP.

Repair did not solve it? Tell us your Outlook version and the error message.

Open a support ticket

SEE ALSO

Outlook is not syncing: missing e-mails and folders that do not update

Outlook is slow, freezes or will not open: safe mode, add-ins and a new profile

POP or IMAP: which to choose, and what you lose by picking wrong

Outlook search does not find e-mails: rebuilding the index

Your mailbox is full: what to delete and how to stop it happening

Common Outlook errors: 0x800CCC0E, password prompts and more

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