A corrupt PST file can lock you out of years of email, contacts and calendar history. The good news is that plenty of Outlook errors that look like corruption aren’t corruption at all, and many real cases clear up with Microsoft’s free Inbox Repair Tool, ScanPST. When ScanPST can’t finish the job, a third-party PST repair tool can rebuild the file and pull back items ScanPST leaves behind.
This guide starts with a quick check that tells you whether you need a repair tool at all. It then walks through ScanPST properly and compares seven paid tools on what actually decides a purchase: what the free trial lets you save, where the tool can export your mail, how it handles passwords and deleted items, and what it costs.
| Quick answer Minor errors and Outlook still opens: run ScanPST first. It’s free and already on your PC if you have classic Outlook.ScanPST failed and you want the mail back in Microsoft 365 or Exchange: Stellar Repair for Outlook (Technician), Kernel for Outlook PST Repair or Shoviv Outlook PST Repair.You lost the PST password: DataNumen Outlook Repair. The vendor says it repairs protected PSTs even when the password is lost.You need to export to webmail, IBM Domino or GroupWise: Kernel for Outlook PST Repair.Small budget: SysTools, Shoviv or Aryson at $49, or Recovery Toolbox Personal at $39 for home use.Many PCs to cover: Recovery Toolbox Site license, $99 for up to 100 devices. |
PST repair tools at a glance
| Tool | Best for | Free trial saves | Starting list price | Exports to Microsoft 365 |
| ScanPST (built into classic Outlook) | Minor structure errors | Repairs the file in place | Free | No |
| Stellar Repair for Outlook | Severe corruption, moving mail to Microsoft 365 | Nothing (scan and preview only) | $99 | Yes (Technician) |
| Kernel for Outlook PST Repair | Widest range of export destinations | 25 items per folder | See vendor site | Yes |
| SysTools PST Repair Tool | Low-cost repairs, encrypted email | 25 items per folder | $49 | Yes |
| DataNumen Outlook Repair | Lost PST passwords, old ANSI files | Demo text replaces message bodies | $249.95 | No (PST output only) |
| Shoviv Outlook PST Repair | Batch jobs with incremental export | 50 items per folder | $49 | Yes |
| Recovery Toolbox for Outlook | Home users and site licenses | 5 items per folder | $39 | No |
| Aryson Outlook PST Repair | Choosing scan depth by damage level | Nothing (preview only) | $49 | No |
List prices from vendor sites, 8 October 2026. Most vendors run frequent sales, so the checkout price is often lower.
Is your PST file actually corrupt? Check this first
Several common Outlook errors look like PST corruption but have nothing to do with damage inside the file, and no repair tool will fix them. Match your symptom below before you spend money.
| Symptom | What’s usually going on | What to do first |
| “The file Outlook.pst is not a personal folders file” right after restoring the PST from a USB drive, DVD or backup | The file is marked read-only, or you tried to bring it in with Import | Copy it to your local drive, clear the Read-only box in its Properties, then open it with File > Open & Export > Open Outlook Data File |
| “Errors have been detected in the file…” with a prompt to run the Inbox Repair Tool | Real damage to the PST’s internal structure | Run ScanPST (next section) |
| “Can’t move the items. The file … has reached its maximum size” | The file hit its size limit. Nothing is damaged | Archive old items or move them to a new PST |
| Outlook won’t start and says “The set of folders cannot be opened” | A damaged default PST or a broken Outlook profile | Run ScanPST on the default PST, then try a new Outlook profile |
| Errors on an .ost file (Exchange or Microsoft 365 account) | The OST is a local copy of a mailbox stored on the server | Close Outlook, delete the OST and reopen Outlook to rebuild it |
| Error 0x8004010F during send/receive | Usually the Outlook profile or the data file location, not a damaged PST | Check the data file path in Account Settings, then create a new profile |
| The PST is gone after a deletion or a drive format | There’s nothing to repair yet | Recover the file with data recovery software first, then repair it if needed |
| A PST on a network drive keeps getting damaged | Microsoft doesn’t support PSTs over LAN or WAN links for everyday use | Move the PST to a local disk |
| Only the new Outlook is installed and the PST won’t open | New Outlook needs classic Outlook on the same PC to open PST files | Install classic Outlook with the same 32-bit or 64-bit version |
One caution on OST files: items that never synced to the server, such as messages created while offline, disappear with the old OST. If the account no longer exists on the server (an orphaned OST), you need an OST to PST converter instead of a rebuild.
On size, Outlook’s limits are defaults rather than hard walls. Microsoft sets the default maximum for Unicode PSTs at 50 GB in Outlook 2010 and later and 20 GB in Outlook 2003 and 2007. Older ANSI-format PSTs, created by Outlook 97 to 2002, stop at about 2 GB. Admins can raise the Unicode limit with the MaxLargeFileSize registry value, though Microsoft warns that performance can drop.
Try the free fix first: ScanPST (Inbox Repair Tool)
ScanPST.exe is Microsoft’s free Inbox Repair Tool. It installs with classic Outlook and fixes structural errors in a PST without any extra software.
Where to find ScanPST
- 64-bit Office (Microsoft 365, Outlook 2024, 2021, 2019 and 2016): C:\Program Files\Microsoft Office\root\Office16
- 32-bit Office on 64-bit Windows: C:\Program Files (x86)\Microsoft Office\root\Office16
- Can’t find it? Open the Microsoft Office folder in File Explorer and type scanpst in the search box.
How to run ScanPST
- Note where your PST lives: in Outlook, go to File > Account Settings > Account Settings and open the Data Files tab.
- Close Outlook completely. If it’s still listed in Task Manager, end it there.
- Copy the PST to another folder. ScanPST makes its own backup, but a separate copy costs nothing.
- Open SCANPST.EXE, select Browse, pick the PST and select Start.
- If errors are found, keep “Make backup of scanned file before repairing” selected and select Repair.
- Run ScanPST again on the same file. Microsoft notes you may need several runs. Stop when it reports no errors.
- Start Outlook with the profile that uses the repaired file.
Keep in mind that ScanPST favors a working file over a complete one. Items it can’t read may not come back.
Run multiple passes automatically (Microsoft 365 and Outlook 2016)
Starting with Outlook 2016 version 1807 (build 16.0.10325.20082), ScanPST can run from a command prompt and repeat scan-and-repair passes until the file stops changing. Microsoft documents these switches:
| Switch | What it does |
| -file | Path to the .pst file to scan |
| -rescan | Maximum number of passes, 0 to 20 (default 10) |
| -force | Runs without waiting for you to click anything |
| -silent | Runs with no window. Watch the log file or Task Manager to see when it ends |
| -backupfile | Name and location of the backup file |
| -log | append, replace or none (default replace) |
Example, from the Office16 folder in an elevated Command Prompt:
scanpst.exe -file “C:\Users\you\Documents\Outlook Files\archive.pst” -rescan 10 -force -log replace
After ScanPST finishes
- Recovered Personal Folders or Lost and Found: Lost and Found holds items Outlook couldn’t put back in their original folders. Create a new data file, move the items into it, then remove the Recovered Personal Folders file.
- Pull more items from the backup: ScanPST saves the original as a .bak file in the same folder. Copy it, rename the copy so it ends in .bak.pst, and import it with the Import and Export Wizard to recover items the repair dropped.
When to stop and use a repair tool
- ScanPST can’t open the file, freezes or crashes
- It still finds errors after several passes
- Folders or items are clearly missing, or Lost and Found is full of items with no names
- The PST is password-protected and you don’t have the password
- You need the mail somewhere else, such as Microsoft 365, Exchange or another file format
How we compared these PST repair tools
We compared each tool on the same eight points, using each vendor’s current product, pricing and requirements pages (checked 8 October 2026), and checked every Outlook claim in this guide against Microsoft’s documentation:
- Outlook and Windows versions supported
- What the free trial lets you save
- Export options, including Microsoft 365 and Exchange
- Deleted item recovery
- Password and encryption handling
- Batch repair of several PSTs at once
- System requirements that could stop you installing it
- Price and license model
Claims that only a vendor makes, such as “no size limit” or a recovery rate, are labelled as vendor claims. The best way to judge any of these tools on your own damaged file is its free trial, so the trial comparison further down matters more than the order of this list.
The 7 best PST repair tools
Each tool fits a different situation, so start with the Best for line.
1. Stellar Repair for Outlook
Best for: severe corruption and moving repaired mail into Microsoft 365
Latest Version: 14.0.0.1 (June 2026)
List price: Professional $99, Technician $199, Toolkit $499, each with a 1-year or lifetime license option
Free trial: scan and preview only, no saving
Stellar scans a damaged PST and previews recoverable email, contacts, calendar items and tasks, with recovered deleted items highlighted in red. Professional saves to PST, EML, MSG, RTF, HTML and PDF. Technician adds MBOX export, PST split and compact, and direct export to Microsoft 365. The vendor says there’s no PST size limit and that it handles password-protected and encrypted files.
The June 2026 release added automatic detection of PST files that need repair, better handling of attachment names in non-English characters, and a filter option for exports to a live Exchange mailbox.
Pros
- Repairs several PSTs in one batch
- Full preview of recoverable items before you pay
- Recovers deleted items as long as they haven’t been overwritten (vendor claim)
Cons
- The trial can’t save anything, so you can’t test real output before buying
- Runs only on 64-bit Windows 8 to 11 and needs at least 8 GB of RAM
- OST conversion needs the Toolkit edition, and the product page isn’t clear about which edition includes live Exchange export
Skip it if: you’re on 32-bit Windows or an older PC with less than 8 GB of RAM.
2. Kernel for Outlook PST Repair
Best for: exporting repaired mail to almost any destination
Latest Version: 26.0 (December 2025)
List price: Home, Corporate and Technician licenses. Edition prices weren’t shown on the product page, so check the order page
Free trial: saves the first 25 items in each folder
Kernel has the longest export list in this guide: 12 file formats, including PST, MSG, EML, PDF, MBOX, DOCX and HTML, plus Microsoft 365, Exchange Server, IBM Domino, GroupWise, Gmail, Yahoo, iCloud, AOL and any IMAP account. It lists support for Outlook versions back to Outlook 97 and for Windows Server 2003 through 2022, which helps when you’re rescuing an old archive on an old server.
It repairs password-protected PSTs but doesn’t remove or recover the password. Kernel offers a separate free tool for that.
Pros
- The 25-items-per-folder trial lets you check real output
- Adds and repairs several PSTs at once
- Recovers permanently deleted emails with attachments (vendor claim)
Cons
- Edition prices aren’t on the product page
- Doesn’t recover a lost PST password on its own
Skip it if: you only need a repaired PST and want clear pricing before you download anything.
3. SysTools PST Repair Tool
Best for: low-cost repairs and email encrypted with S/MIME or OpenPGP
Latest Version: 9.0
List price: $49
Free trial: previews everything and saves 25 items per folder
SysTools offers Quick Scan for minor damage and Advance Scan for severe corruption. It can add multiple PST files, including .bak backup files, and repair them in one run. Exports cover PST, PDF, MSG, EML, HTML and Microsoft 365, including shared mailboxes.
One feature few rivals mention: it can remove S/MIME and OpenPGP encryption from recovered messages, as long as you supply the certificates or private keys and their passwords. It can also split the output PST into smaller files.
Pros
- Low price with a trial that saves real items
- Removes S/MIME and OpenPGP encryption when you have the keys
- Batch repair of PST and .bak files
Cons
- The product page lists Outlook support only up to Outlook 2021
- Size claims conflict: one FAQ says there’s no limit, another says up to 100 GB
Skip it if: you run Outlook 2024 and need it officially listed as supported. Confirm with the vendor first.
4. DataNumen Outlook Repair
Best for: PSTs with a lost password and old ANSI-format files
Latest Version: 10.2 (April 2025)
List price: $249.95 for one user, with lower per-user prices for volume licenses
Free trial: repairs the file but replaces message bodies with demo text
DataNumen focuses on one job, rebuilding a usable PST, and doesn’t export directly to EML, MSG or Microsoft 365. Its strengths are elsewhere. The vendor says it recovers password-protected PSTs even when the password is lost and handles both compressible and high encryption. It can also convert between the old ANSI and current Unicode PST formats, which matters if you’re stuck with a 2 GB ANSI archive.
A Batch Repair tab processes several files in one run. DataNumen claims the highest recovery rate in the category, offers a 30-day money-back guarantee, and says it will refund the order if another tool recovers more.
Pros
- Recovers password-protected PSTs without the password (vendor claim)
- Converts between ANSI and Unicode PST formats
- Volume pricing for larger teams
Cons
- The most expensive single-user license in this guide
- The demo hides real message text, so you can’t judge results before buying
- PST is the only output format, and listed Outlook support stops at Outlook 2021
Skip it if: you need to send the recovered mail straight to Microsoft 365.
5. Shoviv Outlook PST Repair
Best for: batch repairs with incremental export to Microsoft 365 or Exchange
Latest Version: 26.9
List price: $49
Free trial: saves the first 50 items in each folder
Shoviv lets you add any number of PSTs to one job and export to PST (with size splitting), EML, MSG, VCF, ICS, HTML, RTF, PDF, Microsoft 365, on-premises Exchange, an Outlook profile, or IMAP webmail. Its incremental export picks up from the last item it moved and skips items already transferred, which saves hours if a long Microsoft 365 upload gets interrupted.
It also recovers hard-deleted items and can extract email addresses to a CSV file.
Pros
- The largest free trial allowance in this list, at 50 items per folder
- Incremental export avoids duplicates after an interrupted transfer
- Wide range of export destinations for the price
Cons
- The product page contradicts itself on whether classic Outlook must be installed
- Password-protected PST handling isn’t described on the product page
Skip it if: your PST is password-protected and you don’t have the password.
6. Recovery Toolbox for Outlook
Best for: home users on a budget and offices that want one site license
Latest Version: 5.x
List price: Personal $39 (non-commercial use), Business $59, Site $99 for up to 100 devices
Free trial: saves up to 5 items per folder
Recovery Toolbox reads both ANSI and Unicode PSTs and saves results as one or more new PST files or as MSG, EML, VCF and TXT files. It can split output into several PSTs to stay under size limits, and it reads password-protected and encrypted files.
Saving as PST needs Outlook installed, and files over 4 GB need 64-bit Outlook and Windows. The vendor also runs an online repair service at $10 per GB of corrupted file, covered in the privacy section below.
Pros
- Cheapest entry price in this guide
- A site license covers up to 100 devices
- Online option when you can’t install software
Cons
- The 5-item trial is too small to judge much
- Doesn’t export contact groups, and has no direct Microsoft 365 export
- Batch processing isn’t mentioned on the product page
Skip it if: you need to move recovered mail straight into Microsoft 365.
7. Aryson Outlook PST Repair
Best for: matching scan depth to how badly the file is damaged
Latest Version: 17.0
List price: $49
Free trial: preview only, no saving
Aryson gives you three scan levels: Standard for minor damage, Advanced for moderate corruption and Deep for severe cases. For password-protected files, you pick the PST’s encryption type (none, compressible or high) before the scan starts. Exports cover PST, EML, MSG, DBX and MBOX.
Aryson’s product page lists support for Outlook for Microsoft 365 and the new Outlook for Windows. Keep in mind that the new Outlook can only open a PST when classic Outlook is installed on the same PC.
Pros
- Three scan levels for different damage
- Recovers deleted emails and folders after a deep scan (vendor claim)
- Low price
Cons
- The free version can’t save anything
- No direct Microsoft 365 export listed
- The Windows support list on the product page is inconsistent
Skip it if: you want to test real output before you pay.
Also considered: Remo Repair PST (no published price when we checked) and Cigati Outlook PST Repair. General data recovery apps such as EaseUS Data Recovery Wizard and iBoysoft Data Recovery can find a deleted PST, but they aren’t PST repair tools.
Free trial limits: what each tool lets you save before paying
A free trial is the only way to see how a tool handles your specific file, and trial limits vary far more than prices do.
| Tool | What the free version does | Can you check real output? |
| Stellar Repair for Outlook | Scans and previews, no saving | Preview only |
| Kernel for Outlook PST Repair | Saves the first 25 items per folder | Yes |
| SysTools PST Repair Tool | Previews everything, saves 25 items per folder | Yes |
| DataNumen Outlook Repair | Repairs, but replaces message bodies with demo text | Folder structure only |
| Shoviv Outlook PST Repair | Saves the first 50 items per folder | Yes |
| Recovery Toolbox for Outlook | Saves up to 5 items per folder | Barely |
| Aryson Outlook PST Repair | Previews, no saving | Preview only |
To get the most from a preview-only trial, compare the folder tree and item counts in the preview with what you expect. Outlook shows a folder’s item count in its Properties. A tool that shows your full folder structure with realistic counts is a good sign. Missing folders, or hundreds of nameless items dumped in one recovery folder, is a warning.
Pricing and licensing compared
PST repair tools range from a $39 one-time license to $249.95 per user, and the license type matters as much as the price.
| Tool | Entry license | Higher tiers | License term |
| Stellar Repair for Outlook | Professional $99 | Technician $199, Toolkit $499 | 1-year or lifetime option |
| Kernel for Outlook PST Repair | Home | Corporate, Technician | See vendor site |
| SysTools PST Repair Tool | Full version $49 | None listed | Not stated on product page |
| DataNumen Outlook Repair | $249.95 per user | Per-user price falls with volume | Not stated on order page |
| Shoviv Outlook PST Repair | Full version $49 | None listed | One-time price shown |
| Recovery Toolbox for Outlook | Personal $39 | Business $59, Site $99 (100 devices) | One-time |
| Aryson Outlook PST Repair | Full version $49 | None listed | Not stated on product page |
List prices from vendor sites, 8 October 2026.
Personal licenses often rule out business use, and Recovery Toolbox says so explicitly. Technician-style licenses let an IT professional use the tool on client machines. Check the refund policy before you buy, especially for tools whose trial can’t save anything.
Online PST repair: what happens when you upload your mailbox
Online PST repair services fix the file on the vendor’s servers, which means your whole mailbox leaves your PC.
| Service | Price | Size limit | What the vendor says about your file |
| Stellar Online PST Repair | Free for one file. $29.99 per file paid | 500 MB free, 5 GB paid | Repaired files are deleted after 24 hours (free) or 48 hours (paid) |
| Recovery Toolbox online service | $10 per GB of corrupted file | Not stated on the product page | Its own page notes that uploading raises security risks. No retention period is stated there |
For a personal mailbox under 500 MB, an online service is a reasonable shortcut. For work mailboxes that hold client, patient, legal or financial data, use a desktop tool instead. Sending that data to a third party can break your organization’s data protection rules unless a data processing agreement is in place.
PST files in the new Outlook for Windows (2026 status)
The new Outlook for Windows can now open and import PST files, but support is still partial and depends on classic Outlook being installed. Here’s how it arrived, according to Microsoft’s release notes:
| Date | What changed in new Outlook |
| 28 January 2025 | Read-only access to email in PST files (open, read and search) |
| 12 September 2025 | Scheduled auto-export of a mailbox or folder to a PST |
| 10 October 2025 | Read-only view of calendar items in PST files |
| 21 November 2025 | Contacts from PST files shown in People |
| 20 March 2026 | Import email from a PST under Settings > Files > Import |
| 12 June 2026 | PST import extended to calendar events, contacts and tasks |
To open a PST in new Outlook, Microsoft requires classic Outlook on the same PC with the same architecture (32-bit or 64-bit), a Microsoft 365 subscription on the account, and a non-ARM version of new Outlook. Microsoft’s own feature comparison still lists PST support as “partially available.”
What this means for repairs: ScanPST and most repair tools are built around classic Outlook, so repair a damaged PST before you move a PC to the new Outlook, not after. Microsoft says existing classic Outlook installations will stay supported until at least 2029, so there’s no rush to remove it from PCs that still depend on PST archives.
After the repair: check before you delete anything
A repair tool that reports “complete” hasn’t necessarily brought every item back, so check the result before you delete the original file.
- Compare item counts. Right-click your main folders in the repaired file, open Properties and compare the counts with the tool’s preview or with what you expected.
- Open attachments. Test around ten of different types: PDFs, Office files, images and ZIP files.
- Check the calendar. Open three recurring meetings and confirm the pattern and any exceptions survived.
- Empty Lost and Found. Move recovered items into real folders, then remove the Recovered Personal Folders file if ScanPST created one.
- Scan the repaired file. Run ScanPST on it once. It should report no errors.
Keep the original PST and any .bak file until all five checks pass.
Want proof that a tool didn’t write to your original file? Run this in PowerShell before and after the repair and compare the two values. If they differ, the tool changed the original.
Get-FileHash “C:\path\to\file.pst” -Algorithm SHA256
Why PST files get corrupted, and how to stop it happening again
Most PST damage happens when Outlook is interrupted while it’s writing to the file, so prevention comes down to where the file lives and what else touches it.
- Keep PSTs off network drives. Microsoft doesn’t support PSTs over LAN or WAN links for regular use, and a dropped connection can corrupt the file. The one supported exception is Outlook running on Remote Desktop Session Host or VDI, with a fast connection and one Outlook client per file.
- Keep antivirus scans away from open PSTs. Microsoft’s antivirus guidance for Outlook 2010, now archived, warns that file-level scanning of .pst and .ost files while Outlook is running can cause corruption, and recommends scanning attachments instead.
- Watch OneDrive folder backup. When Known Folder Move is set up through Group Policy, OneDrive moves PST files along with your Documents folder, and Outlook may then show errors because it still looks in the old location. OneDrive also syncs PST files less often than other files.
- Close Outlook before backups and shutdowns. Copying a PST while Outlook has it open, or losing power in the middle of a write, are two of the most common causes of damage.
- Stay well under the size limit. Archive by year so no single file creeps toward the 50 GB default.
- Retire old ANSI files. If you still have a PST in the Outlook 97 to 2002 format, move its contents into a new Unicode PST before it nears 2 GB.
Under the hood, a PST tracks its data through B-tree indexes. When an index breaks, intact messages can look lost, which is why repair tools can often find items Outlook can’t see.
FAQs
Is there a free PST repair tool?
Yes. ScanPST, Microsoft’s Inbox Repair Tool, is a free PST repair tool that installs with classic Outlook. It handles minor structural damage well. For severe corruption, lost passwords or exports to other formats, you’ll need a paid tool, and the free trials above let you check results first.
Is ScanPST safe to use?
ScanPST is safe in that it creates a backup before it repairs a file, but it can discard items it can’t read. Microsoft recommends backing up your PST before you start, so copy the file first and keep the .bak file ScanPST creates until you’ve checked the result.
Can I repair a PST file without Outlook installed?
You can’t run ScanPST without Outlook, because it installs with classic Outlook. Some third-party tools can scan and export without Outlook (SysTools says its tool can), while others, including Recovery Toolbox, need Outlook installed to save results as a PST. Check the requirements page before you buy.
Can a PST repair tool fix a file encrypted by ransomware?
A PST repair tool usually can’t restore a PST that ransomware has fully encrypted. If only part of the file was encrypted, some tools can pull out the readable parts, but expect missing items and a damaged folder structure. Restore from a backup first and treat repair as a last resort.
Can I repair a PST file on a Mac?
You can’t repair a PST on a Mac with the tools in this guide, because they’re Windows apps. Outlook for Mac can import a PST created in Outlook for Windows, so repair the file on a Windows PC or a Windows virtual machine first, then import the repaired copy on your Mac.
How do I know a repair didn’t lose emails?
You can tell a repair didn’t lose emails by comparing item counts folder by folder with the tool’s preview or the original, opening a sample of attachments, and checking recurring meetings. The five-step check above takes about ten minutes.
Final verdict
Start with the free checks. Rule out read-only files, size limits and OST problems, then run ScanPST a few times. If your mail still isn’t back, choose by situation: Stellar, Kernel or Shoviv when the mail needs to go to Microsoft 365 or Exchange, DataNumen when the password is lost, Kernel when you need unusual export targets, and SysTools, Shoviv, Aryson or Recovery Toolbox when budget comes first.
Whichever tool you pick, run its free trial on a copy of your PST, not the original, and go through the five-step check before you delete anything.
