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How to export Outlook, Hotmail or Microsoft 365 e-mail for a court case
Outlook is the one major provider with no direct export to mbox, the standard format mail-review and e-discovery tools read. Its native .pst format is proprietary and poorly supported outside Microsoft's world. The reliable free route: let Thunderbird — Mozilla's open-source mail client — sync your account, then export from there. The same procedure works for Hotmail, Live, Microsoft 365 and any IMAP provider.
Updated 2026-07-20 · Windows and Mac · ~45 minutes, mostly waiting for sync
Install Thunderbird
Download it free from thunderbird.net (Windows and Mac) and install. Thunderbird has been Mozilla's mail client for twenty years — open source and safe.
Add your Outlook account
On first launch, enter your name and your Outlook/Hotmail/Microsoft 365 address. Thunderbird detects the settings automatically and sends you to Microsoft's own sign-in page to approve access (Thunderbird never sees your password; you can revoke its access from your Microsoft account later).
Let it sync — completely
Thunderbird now downloads your mail. Leave it open; years of e-mail can take a while. Two settings to check under Account Settings → Synchronization & Storage: message synchronization is on for all folders, and Don't download messages older than… is unticked — you want the full history. Then force the full download with File → Offline → Download/Sync Now… and wait until the status bar goes quiet — Thunderbird otherwise fetches bodies lazily, and an export made too early ships incomplete messages without warning.
Install the “ImportExportTools NG” add-on
Menu → Add-ons and Themes, search for ImportExportTools NG, click Add to Thunderbird.
Export each folder as mbox
Right-click a folder — start with Inbox — then ImportExportTools NG → Export folder → mbox and choose a destination. Repeat for Sent and every other folder that matters. Your own sent mail is often the most important evidence — don't skip it.
What to do with the mbox files
You now have one mbox per folder — a complete, portable archive, but not yet a workspace. The next stage is making the whole history searchable so filtering by person, period and topic replaces scrolling: see How to organize ten years of e-mail for your lawyer.
You have the export — now find the evidence in it
ExhibitMail turns your mbox files into a searchable, scored body of evidence: upload them, describe the dispute, and AI ranks every message by how much it matters to your case. Ask questions in plain language, get answers cited to the source e-mails, and invite your attorney for free.
Start your case — freeFree to start: upload and try it on your own e-mail before paying anything. Every case encrypted at rest under its own key.
Frequently asked questions
Why not just export a .pst from desktop Outlook?
.pst is Microsoft's proprietary container; many review tools read it badly or not at all (ExhibitMail doesn't accept .pst yet either). The Thunderbird route produces standard mbox files every tool understands — and it works even if you don't have desktop Outlook, because Thunderbird talks directly to the server.
Is it safe to sign in to Thunderbird with my account?
Yes. Thunderbird is Mozilla's open-source mail client. The sign-in happens on Microsoft's own page (OAuth) — Thunderbird never handles your password — and you can revoke its access afterwards under your Microsoft account's security settings.
The sync is taking forever — is that normal?
For a decade of mail, yes: hours is normal, and it's worth the wait. Let it run overnight if needed. The export itself is fast once the sync is done.
My e-mail is with another provider (Yahoo, company server, …)
The identical route works for any provider with IMAP access: add the account to Thunderbird, let it sync fully, export each folder as mbox. Only the sign-in step differs per provider.
This guide is general information about exporting e-mail, not legal advice. For what to do with the evidence in your specific case, talk to your attorney.