Stellar Repair for Outlook Review: Desktop vs Online PST Repair, Tested

Sponsored review. Stellar paid for this post and supplied the licence and the test file. They checked the draft for technical accuracy. We installed, ran and timed both products ourselves on 27 October 2026, and the results, the cons and the verdict are ours.

A corrupt PST rarely announces itself politely. Outlook hangs on "Processing", throws an error about the data file, or opens with half your folders missing. Microsoft's own fix, ScanPST, handles light damage and gives up on anything worse.

So we took one damaged mailbox and ran it through both of Stellar's options for Outlook PST repair: the Stellar Repair for Outlook desktop app and the newer Stellar Online PST Repair service in the browser. Same file, same day, same machine. This is what happened, including the parts that didn't go to plan.

If you read our earlier look at Stellar Repair for Outlook from 2025, this is the follow-up: a newer version, a second product and harder numbers.

The short version

• The desktop app did the job. It rebuilt the whole folder tree of our corrupt file in about 3 minutes, showed every email, contact and calendar entry before saving, and produced a PST that ScanPST rated as healthy apart from minor inconsistencies.
• It needs classic 64-bit Outlook installed. No Outlook, no repair. We found that out the hard way.
• The online service is quick and needs no install, but "free" means one file up to 500 MB, you need an account, and the preview is a list of folder names, not your actual emails.
• For a mailbox that matters, buy the desktop app. For a small personal PST on a machine you can't install software on, the online tool is worth a go.

How we tested

We checked the installer before running it: it came from Stellar's own product page, carried a valid code-signing certificate in Stellar Information Technology's name, and Windows Defender found nothing.

The baseline: what ScanPST made of the file

Before touching Stellar, we pointed ScanPST at a copy of the original file. It found errors and could see 42 folders and 51 items.

Remember those two numbers. They are the yardstick for everything below.

Stellar Repair for Outlook (desktop app)

Installing and activating

Setup is a standard Windows wizard: language, licence agreement, install folder (it needs about 200 MB), Start Menu folder, desktop shortcut. It took about 3 minutes. Nothing else was bundled in.

One small irritation: clicking Finish also opened a Stellar "installation successful" web page in the browser without asking.

Activation sits under its own tab. Paste the key, click Activate, and a few seconds later it says "Activation complete."

The catch: you need classic Outlook

Our test machine only had the new Outlook app that ships with Windows 11. The moment we clicked Select Outlook Data File, Stellar stopped us:

The product page lists Windows versions, processor, RAM and disk space. We didn't see Outlook mentioned in what we read. It should be in bold at the top, because it rules out two common situations: a machine where you uninstalled Outlook because it kept crashing, and anyone who has already moved to the new Outlook.

We installed classic 64-bit Outlook through Microsoft's Office Deployment Tool (about 20 minutes and 6 GB of disk), relaunched Stellar, and the error was gone. Outlook doesn't need to be signed in or activated for Stellar to use it.

Running the repair

Select Outlook Data File gives you two routes: let it search for your Outlook profiles, or choose the file yourself. We chose manually, browsed to the PST and clicked Repair.

It works in two passes. First it analyses the file, then it rebuilds the folder tree one folder at a time, and you can watch folders appear on the left as it goes.

About 3 minutes later it reported "Selected file has been repaired." The tree held 60 emails plus everything else: Inbox (56), Lost&Found (17), Tasks (8), Journal (7), Notes (6), Calendar (2), Deleted Items (2) and a Contacts folder, along with Outlook's hidden Recoverable Items folders.

Checking what came back before you save

This is the part that earns the licence fee. You can open every recovered item before you commit to saving anything.

Deleted emails appear in red. We opened one: full formatted HTML body, sender, recipients and all three attachments (a JPG, a PDF and a PNG) intact. The preview pane was slow the first time, taking about 8 seconds and flashing "Can't reach this page" before the message rendered.

The calendar view has day, work week, week and month layouts. Both appointments came back with their times.

The contact card came back whole: name, three email addresses, company and account number. The Contacts view opens blank until you click a contacts folder, which confused us for a moment.

Saving the repaired file

Save Repaired File offers PST, MSG, EML, RTF, HTML and PDF. Stellar says the higher Technician edition can also export straight to Microsoft 365 and live Exchange. We tested Professional, which doesn't.

Look closely at the next screen:

"Recover deleted items" is unticked by default. You have just spent five minutes looking at deleted emails in red in the preview, and unless you tick this box, they won't be in the file you save. We ticked it. Auto split PST file is on by default, which keeps large outputs manageable.

Saving took about 2 minutes. The new file was 376.86 MB, three times the size of the 125 MB original, so plan for that much free space.

The independent check

We ran ScanPST again, this time on Stellar's output. It took about 14 minutes on the larger file and came back with:

Nearly double the items, and a file Microsoft's own tool no longer flags as broken. Part of the jump is the deleted items we asked Stellar to keep. It isn't spotless by ScanPST's standard, and we'd rather say so than pretend otherwise, but "minor inconsistencies, repair optional" is the result you want.

We didn't open the repaired PST in a signed-in Outlook profile on camera. Our test install of Office was unactivated, and we weren't going to put a real mailbox account into a test VM.

Stellar Online PST Repair

The online service lives at repair.stellarinfo.com/outlook and promises a fix "within 15 mins" with no installation.

Sign-in comes first

The page headline says free, but the upload button says "Sign In & Upload". Click it and you get a login box: Google, or email and password, or sign up. There is no anonymous option.

Upload, repair, preview

Once signed in, a three-step tracker runs Upload PST, Repair PST, then Preview & Save. Our 125 MB file uploaded in about a minute.

Start Repair moved through Analyzing, Repairing and Generating Preview. About 5 minutes later, 8 minutes after we started the upload, it reported "File Repaired Successfully".

The preview disappointed. It downloads a small HTML file showing the folder tree and item counts. You can't open a single email, contact or appointment. The counts matched the desktop app exactly (Inbox 56, Lost&Found 17, Tasks 8 and so on), so the repair engine looks the same. You just can't see your data before you take it.

What's free and what isn't

Clicking Save PST File brings up the plans:

Prices as shown on 27 October 2026.

The free download worked. We got a 339 MB repaired PST in about a minute, with a valid PST header.

Privacy

Your mailbox leaves your computer. The preview link pointed to Amazon S3 storage in Frankfurt (eu-central-1). For a personal mailbox, that may be fine. For a client's or employee's mailbox, check your own obligations before uploading, and read Stellar's privacy policy for how long files are kept.

Desktop vs online: side by side

When to use each

Use the online service when the PST is under 500 MB, you can't install software on the machine, Outlook isn't installed, and the mailbox isn't sensitive. It is quicker to start and genuinely needs nothing on your computer.

Use the desktop app when the file is large, the mailbox is confidential, you need to check specific emails before trusting the result, or you will repair more than two or three files. At US$29.99 a file online, the US$79 desktop licence pays for itself on the third.

Pros and cons

What we liked

• The desktop repair was fast and complete on our file: full folder tree in about 3 minutes.
• Full preview before saving, including deleted items, attachments, calendar and contacts.
• ScanPST went from "errors found, 51 items" to "minor inconsistencies, 99 items" after the repair.
• Six output formats from the desktop app.
• The online service needs no install and no Outlook, and the free tier really does give you the repaired PST.

What we didn't

• The desktop app won't work without classic 64-bit Outlook, and the product page doesn't make that obvious.
• "Recover deleted items" is off by default when saving.
• The repaired file was three times the size of the original.
• The online preview shows folder counts, not your emails, and the free tier stops at 500 MB.
• You must create a Stellar account to use the "free" online repair.
• Setup opens a marketing page in your browser without asking.

Verdict

Stellar Repair for Outlook did what ScanPST couldn't on our test file: it rebuilt the mailbox, let us check the emails, calendar and contacts before saving, and handed back a PST that Microsoft's own tool rated as healthy apart from minor inconsistencies. The Outlook requirement and the unticked deleted-items box are real annoyances, and both are easy to work around once you know about them.

The online service is a useful first try for a small personal PST. For anything bigger than 500 MB, anything confidential, or any mailbox you need to check line by line, buy the desktop app.

You can download Stellar Repair for Outlook from Stellar, or try the Stellar Online PST Repair service on a file under 500 MB first.

If your problem sits on the server side instead, our guide to mounting an Exchange database after a dirty shutdown with Eseutil covers that.