Online Exchange Repair
Exchange administrators tend to meet EDB corruption at the worst possible time: a database that refuses to mount after an unclean shutdown, transaction logs that went missing with a failed disk, or an ESEUTIL /p run that finished but left the mailboxes unreadable.
The traditional fix is to install Stellar Repair for Exchange (or a competitor) on a Windows box, point it at the EDB, and wait.
Stellar now offers a browser-based alternative, Free Online Exchange Database Repair, which promises to analyse and repair an uploaded EDB file in the cloud and hand back the mailboxes as PST files, with nothing to install and no Exchange Server or Outlook required.
We put that promise through a real run rather than reading the brochure. Below is exactly what we did, how long each stage took, what came back, and what we checked afterwards to confirm the recovered PST files actually contained what the preview said they did.
The test was carried out from a MacBook Air running Google Chrome, signed in to the service with a Google account.
Stellar supplied several sample EDB files of different sizes for the review; we picked natasha.edb because at 247.94 MB it sits comfortably under the 500 MB ceiling of the free plan, so every step below reflects what a free user gets.
The other samples (384 MB, 512 MB and 846 MB) will be used for the desktop-software part of this review.
Before uploading anything we looked at the file itself. natasha.edb is 259,981,312 bytes on disk, an Extensible Storage Engine database with the 0x620 format version and a 32 KB page size, i.e. an Exchange 2013-era mailbox database created on a Windows Server 2012 host.
One detail worth noting for transparency: the ESE header of this particular sample indicates a dirty shutdown state.
This means the test also evaluates Stellar’s ability to parse and extract data from a database in a dirty-shutdown condition. We will also use a deliberately damaged database for the desktop test.
| Item | Detail |
| Service | Online Exchange Repair by Stellar (repair.stellarinfo.com/exchange) |
| Plan tested | Free (up to 500 MB, one EDB file, preview and download for 24 hours) |
| Browser / OS | Google Chrome on macOS (MacBook Air) |
| Test file | natasha.edb, 247.94 MB (259,981,312 bytes), ESE 0x620, 32 KB pages |
| Sign-in | Google account (email/password sign-up also offered) |
| Date | 16 September 2026, 20:00 to 22:01 IST |
The landing page is a single call to action: a “Repair EDB File” button that first asks you to sign in. There is no way to upload anonymously; the account is what ties the repair job to you so that you can come back for the download within the retention window.
The cookie banner offers a “Reject All” option, which we used, and the sign-in dialog offers Google or email plus password.
Screenshot 1: The upload page after signing in. The button now reads “Upload upto 5GB”, which is the Premium ceiling; free users are still capped at 500 MB.
One small snag we hit here is worth knowing about: the upload is a plain browser file picker, so the EDB has to be on the machine you are browsing from. There is no option to pull the file from a URL, S3 bucket or network share.
For a 248 MB file on a normal office connection this is fine; for a multi-gigabyte Premium upload you will want a fast, stable link, because a dropped browser tab means starting over.
As soon as the upload finished, the page switched to a three-step tracker (File Uploaded, Repair EDB, Preview & Save) and a progress bar.
The wording changes as the job moves through phases: “We are Analyzing the EDB File”, then “Repairing EDB file”, then “Generating Preview”. Nothing has to be clicked; the job runs unattended on Stellar’s side.
Screenshot 2: Upload complete. The file name and size are echoed back and the analysis phase starts automatically.
We logged the progress messages against the clock so that the timings below are real rather than estimated:
| Time (IST) | Status shown on page |
| ~21:05 | Upload complete, “File Uploaded” ticked |
| 21:07:15 | We are Analyzing the EDB File (16%) |
| 21:08:06 | Analyzing (22%) |
| 21:09:14 | Repairing EDB file (60%) |
| 21:09:25 | Repairing EDB file (74%) |
| 21:09:50 | Generating Preview (1%) |
| 21:10:37 | Generating Preview (5%) |
| 21:11:54 | “File Repaired Successfully” with Preview and Save PST Files buttons |
Screenshot 3: Repair phase at 74 percent. The percentage counter is not linear (the preview stage jumped from 5 percent to done in about a minute), so treat it as a heartbeat rather than an ETA.
From upload complete to a finished repair took roughly six and a half minutes for a 248 MB database, which is well inside the “repair within 15 minutes” figure Stellar prints on the landing page.
Screenshot 4: Job complete. The tracker shows all three stages ticked and offers a Preview (HTML) or a PST download.
Clicking Preview downloads a 69 KB HTML report rather than opening a viewer in the browser. The report is served from an Amazon S3 bucket in the eu-central-1 (Frankfurt) region through a pre-signed link that expires after one hour, which is a sensible way to hand out per-user files without exposing the bucket.
Opening it locally shows a folder tree for every mailbox found in the database, with an item count against each folder.
For natasha.edb the report listed four mailboxes and 1,336 items in total. One user mailbox held almost everything: 1,129 items in Inbox, 120 in an “amazon” subfolder, 39 in Deleted Items, 20 in a “Flipkart” subfolder, 19 in Sent Items, 7 calendar entries and 1 in Outbox, for 1,335 items.
A HealthMailbox held a single system message, and two further mailboxes (an in-place archive and a second user) were present but empty.
The preview also preserved the mailbox’s custom subfolders and even a couple of oddly named user folders (“Outboox2”, “outbox 3”), which is a good sign that the folder hierarchy is being read faithfully rather than mapped to defaults.
The preview is, by design, a structural one: Stellar describes it on the page as a view of the mailbox folder structure and item counts, and that is exactly what it delivers.
It is enough to confirm that the database was parsed, that every mailbox was found and that the item totals look right before you download.
Message-level preview, where you open individual emails and attachments before saving, is a feature of the desktop software rather than the online service.
The Save PST Files button does not start a download straight away. It first opens a plan comparison (Free, Premium at $99.99 per file, and the $399 Corporate desktop edition), with a green “Download PST File” button in the Free column.
During our original run this button carried a different label; Stellar corrected it within days of our test, and the screenshot below shows the current wording.
Screenshot 5: The plan modal that appears when you click Save PST Files. The Free column’s “Download PST File” button delivers the recovered mailboxes as a ZIP of PST files; the modal also spells out the Free allowance of one EDB file up to 500 MB.
Clicking it moved us to a small account dashboard (/exchange/portal/dashboard.html) that shows the plan, a “Used/Total 1/1” counter and the repaired file, which switches to a “Preparing Download” state while the archive is packaged.
The PST files inside the archive are timestamped 21:16 IST, so the server had them ready within a minute of the click.
RecoveredPST.zip (44.6 MB) then transferred to the Downloads folder; on our office connection that transfer was slower than the repair itself, which Stellar attributes to link speed on the client side rather than the service, and which its own testing did not reproduce.
The dashboard remains available for the 24-hour retention window, so a download can be repeated if a first attempt is interrupted.
A recovery tool review is only as good as the check you run on its output, so we unpacked the ZIP and inspected every PST with an independent parser (libpst 0.6.76) rather than trusting the report.
| PST file | Size | Items (libpst count) | Preview said |
| carlis jener.pst | 165,594,112 bytes | 1,335 (1,324 emails, 11 appointments) | 1,335 |
| HealthMailbox-PC16-natasha.pst | 271,360 bytes | 1 email | 1 |
| In-Place Archive -HealthMailbox-PC16-natasha.pst | 271,360 bytes | 0 | 0 |
| James OO7.pst | 271,360 bytes | 0 | 0 |
Every file identified as a Microsoft Outlook Unicode PST (format version 23), which is the current format and will open in any Outlook since 2003 and import cleanly into Exchange or Microsoft 365 via New-MailboxImportRequest or the Microsoft 365 import service.
The item counts matched the preview exactly, which is the number we cared most about. Exporting the main PST to standard mailbox files gave us 1,285 mail items across Inbox, its two subfolders, Sent Items and Outbox (the parser skips Deleted Items by default, which accounts for the difference from 1,335), with 1,284 carrying a subject line, 1,364 attachment parts in total, and message dates running from July 2017 to January 2019. Only a single message came out without a readable body.
The appointments came through as iCalendar entries. We did not find truncated attachments or mangled folder names in the sample we opened.
The main PST is 165 MB for a mailbox that occupied most of a 248 MB database, which is about what you would expect once Exchange’s own overhead and the three near-empty mailboxes are set aside. In other words, nothing obvious was left behind.
| Free | Premium | Desktop (Corporate) | |
| Price | $0, no card | $99.99 per file | $399 |
| Max EDB size | 500 MB | 5 GB | No limit |
| Files | One EDB | One EDB | Unlimited |
| Output | PST in ZIP | PST in ZIP | PST, Live Exchange, Microsoft 365 |
| Retention | 24 hours | 48 hours | Local, offline |
The Free tier is a genuinely usable free tier, not a teaser: we completed a full repair and download without entering a card.
The plan is one EDB file per free account, which the site states up front (“Repair Single EDB file”) and the dashboard counter confirms, so a second database means the Premium plan or the Stellar Repair for Exchange desktop software.
Premium at $99.99 per file makes sense for a single EDB File; anyone who expects to do this more than three or four times is better off with the desktop licence, which also removes the size cap, the retention clock and the need to upload company mail to a third party at all.
Because the whole point of this product is uploading a company’s mailbox database to someone else’s server, we paid attention to how that is handled. The upload runs over TLS and the site carries an SSL certification badge.
Uploaded files and recovered artefacts are stored in AWS S3 (eu-central-1, Frankfurt) and are handed out only through short-lived pre-signed URLs (one hour in our test).
Stellar states clearly on the page that uploaded and recovered data is deleted automatically after 24 hours on the Free plan and 48 hours on Premium.
The processing is described as fully automated with no human access, and the original file is never modified because the service reads it and writes new PSTs.
Both the upload and the download go through Amazon S3 using pre-signed URLs, so the storage bucket itself is never exposed and each link is tied to a single job and a short validity window.
Together with the published deletion schedule and the read-only processing model, that is a set of controls for a service whose input is, by nature, an organisation’s complete mail history.
Organisations with strict data-residency requirements can use the desktop edition, which keeps the database on their own hardware throughout.
For the scenario it is built for, a single, modestly sized EDB that will not mount and an administrator who does not have a Windows box with desktop tool to hand, Online Exchange Repair by Stellar did the job in our test quickly and without drama, and the recovered PSTs stood up to independent inspection.
The few rough edges we noted have either been fixed already or are minor next to what the recovery engine delivers. If your database is under 500 MB, this is a free, low-effort first attempt that is worth making before anything else.
Above that, the $99.99 per-file price is fair for a one-off, while organisations that repair databases regularly, need message-level preview, or must keep data on their own hardware will be better served by the desktop edition, which we will cover in Part 2.
GBHackers rating (online service): 4.5 / 5 fast, accurate recovery on a free tier; message-level preview and direct Exchange/M365 export remain desktop-only features.
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