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If Outlook can’t open a damaged PST, make a separate copy of the file and try Microsoft’s Inbox Repair Tool (ScanPST) on a Windows computer before choosing another repair option. ScanPST is Microsoft’s recommended first step for local Outlook data-file errors, but it may take several passes and cannot recover everything. If it does not solve the problem, weigh third-party desktop software against an online service by where your mail is processed, the service’s file limits and retention terms, and whether Outlook is required.
First, confirm that the problem is a PST file
A PST is an Outlook data file stored on your computer. Microsoft lists errors such as “Outlook can’t open your data file” and “Outlook can’t open the set of folders” among situations where the Inbox Repair Tool may help. ScanPST checks the local data file; it does not connect to or analyze mail stored in an Exchange mailbox. Microsoft’s guidance for repairing Outlook data files distinguishes local file repair from mailbox troubleshooting.
Do not treat a damaged Exchange OST as if it were a PST. Microsoft says Outlook can delete and recreate an Exchange offline data file; a PST is a separate file and calls for a different recovery decision.
Make a separate backup before repairing
Copy the PST to another safe location before you run a repair. Microsoft Support recommends backing up the existing Outlook data file first. ScanPST also creates a backup during repair by default, but keeping your own untouched copy gives you a separate recovery point if the repair changes or removes damaged data.
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Try Microsoft’s Inbox Repair Tool
- Close Outlook. The repair tool works on the local data file, so exit Outlook before selecting the PST.
- Find and start SCANPST.EXE. The tool is included with Outlook installations, but its location varies by Outlook version and installation. Search your computer for
SCANPST.EXEif you do not know where it is installed. - Select the PST and scan it. Review the scan result. If errors are found, choose Repair.
- Run another scan if needed. Microsoft Learn notes that the tool may need several passes to fully repair a PST. Keep the original and your separate backup while you work.
- Open Outlook and inspect the recovered data. Look for recovered items in folders named Recovered Personal Folders or Lost and Found, then check the mail and folders you need.
ScanPST validates and corrects internal PST structures. Microsoft says its repair process may remove unreadable or corrupted blocks or items, so a completed repair is not a guarantee that every message or attachment has been restored. Permanently deleted items or data that is too damaged may not be recoverable. The tool also logs its repair activity.
If ScanPST is not enough, compare the trade-offs
Other repair products differ in where they process your mailbox, their requirements, limits, and terms. Claims below about particular commercial products come from their vendors, not independent comparative testing.
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| Option | Where processing happens | Limits and cost | Requirements and cautions |
|---|---|---|---|
| Microsoft ScanPST | On your Windows computer | Included with Outlook; no general current file-size cap is stated on the cited Microsoft support page. | Requires an Outlook installation and access to the local PST. Microsoft says some data may not be recoverable. |
| Third-party desktop software | Product-specific. Stellar says its desktop tool processes the file locally. | Product license and limits depend on the vendor. Stellar advertises no size limit for its desktop edition. | Requirements vary. Stellar says Outlook is needed to complete the repair and save recovered data. These are vendor statements, not independent test results. |
| Online repair service | The PST must be uploaded to the service. | Stellar advertises free repair for one file up to 500 MB and a paid tier for files up to 5 GB at $29.99 per file. | Requires upload and browser access. Stellar says free-tier files are available for download within 24 hours and paid-tier files within 48 hours, after which they are permanently deleted. Limits, price, and retention are vendor claims and may change. |
For the product-specific statements, see Stellar’s online PST repair page and Stellar’s desktop PST repair page. Check the current product terms before relying on a price, limit, retention period, or security description.
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Choose based on privacy, requirements, and recovery needs
- Prefer a local process? ScanPST runs on your Windows computer. A third-party desktop tool may also process locally, but confirm that behavior and its other requirements for the specific product.
- Considering online repair? Uploading sends the PST to the service. Do not upload work, regulated, or otherwise sensitive mail unless doing so is permitted by your organization’s rules and acceptable to you. Review the service’s current handling, retention, and deletion terms before sending the file.
- Need to recover a large file? Compare the product’s current file-size cap with your PST’s size. The online limits and desktop claims in the table are specific to Stellar’s advertised products, not universal industry limits.
- Need particular Outlook features? Check whether the product requires Outlook to be installed or running to finish recovery or save data.
- Need confidence about recovery? No independent head-to-head repair benchmark or recovery-rate figure is established here. Do not assume that a paid tool, an online service, or a successful scan will restore every item.
When to stop and preserve the file
If the recovered folders are incomplete, stop before making further changes to the only copy of the PST. Keep the original and backup, and inspect the repair log and recovered folders. When the mail is important, consider whether another attempt is worth the risk to the file; no repair option can promise complete recovery from severe corruption.
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Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
