When an employee leaves and their mail ends up as a PST file, the safest way to review it is to open a copy read-only, search for what the business needs, and hand that over as files, rather than loading the whole archive into someone else’s Outlook. PstVault does this on a Windows PC without Outlook: it opens the PST read-only, filters by sender, recipient, subject, body and date, and exports the results as EML, a bookmarked PDF or offline HTML, with a JSON report listing the SHA-256 of every file written. For a live Microsoft 365 mailbox, start with Microsoft’s own offboarding steps.
This guide is for the small-business admin or outside IT provider who gets the request: “Can you find the emails about the Henderson account in Sam’s old mail?”
Search a former employee’s PST read-only and hand over only what was asked for.
Get it from Microsoft
Where does a former employee’s PST come from?
Usually one of these:
- An export at offboarding. Microsoft’s guide to saving the contents of a former employee’s mailbox describes adding the mailbox to the Outlook desktop app and exporting it to a .pst file.
- Local archives. Older Outlook setups with POP or IMAP accounts, or AutoArchive, kept mail in PST files on the user’s PC or a network share.
- A backup. The PST turned up on an old laptop image or external drive.
Should I use a PST at all, or a Microsoft 365 option?
If the mailbox still exists in Microsoft 365, the built-in options are often better than a file.
| Option | What Microsoft says | Good for |
|---|---|---|
| Convert to a shared mailbox | Keeps existing email and calendar; the user mailbox needs a license to convert; shared mailboxes without a license are limited to 50 GB | A colleague taking over the role and the address |
| Litigation or in-place hold, then inactive mailbox | Content searchable with eDiscovery tools; Microsoft calls this much more complicated and worth it when litigation is possible | Legal and compliance retention |
| Export to PST through Outlook desktop | Add the mailbox to Outlook and export to .pst | A portable copy before the account goes |
Sources: Microsoft Learn, Step 2, save the contents of a former employee’s mailbox, and Convert a user mailbox to a shared mailbox, checked on 17 October 2026.
If litigation is possible, talk to counsel before you touch anything, and use the hold and eDiscovery route. A desktop viewer is not a legal hold or a defensible collection tool.
Once the mailbox is gone and all you have is the PST, you need a way to read it.
Why not just attach the PST to a colleague’s Outlook?
It works, and it is free if Outlook is installed. It also has costs:
- The archive mixes with their live mail. Search results blend the two, and items can be moved or deleted by accident.
- The whole archive becomes visible to the person, when they may only need one client’s mail. Personal mail and HR matters come along too.
- It changes the file. Outlook can move, copy and delete items in an attached PST.
A cleaner pattern is for IT to search the PST and hand over a defined set of messages.
How do I review a former employee’s PST with PstVault?
PstVault opens Unicode PST files, the format created by Outlook 2003 and later, without Outlook or a mail profile.
- Work on a copy. Copy the PST to a local folder on the reviewing PC and keep the original untouched.
- Open it read-only. Choose Open PST. PstVault never writes to the file and lists every folder with its message count.
- Search for the request. Pick All folders, then type the client’s domain as the sender, or a project name as the subject. More filters adds body text, recipient and a date range. Results are listed newest first, and a body search shows how many messages it has searched.
- Review the hits. Select each result to read headers, folder and attachments. Leave out anything outside the request.
- Export the set. Choose a format: EML for mail apps, one combined PDF with a bookmark per message for reading and printing, or offline HTML. Turn on Also save original attachments as files if the attachments matter.
- Keep the report. The JSON report lists every item with its folder path and subject, the file it became, and the size and SHA-256 of every file written, so you can show what was handed over.
Run the next “find Sam’s emails about this client” request through PstVault in the 15-day free trial.
Get it from Microsoft
Which format should I hand over?
| Recipient | Format | Why |
|---|---|---|
| Colleague continuing the work | EML with attachments | Opens in most mail apps, keeps headers and originals |
| Manager or owner who wants to read | One combined PDF, bookmarked | One file, prints well, no mail app needed |
| Accountant | PDF with PDF and image attachments appended as pages | The email and the invoice in one place |
| Anyone without Outlook | Offline HTML | Opens in a browser, loads no remote content and runs no scripts |
| Sales or CRM migration | Contacts as CSV or vCard 4.0 | Imports into most CRMs and phones |
More detail in EML vs PDF vs HTML for email archives.
What should the handover record show?
Keep a short note with each request: who asked, what the search terms and date range were, the number of items exported, and the JSON report. If someone later asks what was shared, the report’s SHA-256 values let you show that a given file is the one you exported. For more on hashes, Microsoft documents the built-in Get-FileHash cmdlet, which defaults to SHA-256.
What will PstVault not do?
- It does not open OST files or claim ANSI PST support. It opens Unicode PST.
- It does not import into a mailbox. It exports files.
- It is not eDiscovery. No legal hold, no custodian management, no load files. Use Microsoft Purview or a review platform when the matter calls for it.
- It does not redact. If a handover PDF needs redaction, do that in a PDF editor afterwards.
Frequently asked questions
Does reviewing the PST change it?
Not with PstVault. It opens the PST read-only and never writes to it. Exports are new files, and an existing file is never replaced.
Do I need Outlook or a Microsoft 365 license on the review PC?
No. PstVault reads the PST directly, with no Outlook install, no profile and no sign-in.
Can I search the message bodies?
Yes. More filters adds body text, recipient and a date range, and the filters cover the selected folder and everything under it.
Does PstVault upload anything?
No. It runs in the Windows app sandbox, makes no network connections, has no account and collects no telemetry. That matters when the mail contains client or staff information.
Which PCs does it run on?
Windows 10 version 2004 or later and Windows 11, on x64 or ARM64, with 4 GB of RAM; 8 GB is recommended for archives above 50,000 messages.
Try PstVault
PstVault is a one-time purchase in the Microsoft Store, with a 15-day free trial. Open a copy of the PST, run the search, and export a test set. For background, see what is a PST file, export PST to PDF and the PstVault product page.
Answer the request, hand over the files, and keep the record.
Get it from Microsoft
Microsoft, Outlook, Microsoft 365, Microsoft Purview and Windows are trademarks of the Microsoft group of companies. Other names are trademarks of their owners. PstVault is not affiliated with or endorsed by Microsoft.
Last updated 17 October 2026. Published by Automata Labs, a software company in Canada.