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How to export a mailbox from Apple Mail for a legal case
If your correspondence lives in Apple Mail on a Mac, getting it out is a few clicks — Mail exports any mailbox in the standard mbox format that mail-review and e-discovery tools read. The only trap is that the real file hides inside a package; this guide covers that step too.
Updated 2026-07-20 · Apple Mail on macOS, all recent versions
First: make Mail download everything
Apple Mail exports only what is stored on your Mac — and with Limit Mail Storage (storage optimization) on, most older messages exist locally only as stubs, so the export comes out nearly empty. Go to Mail → Settings → Accounts → your account → Account Information and disable the storage limit / choose to keep all messages and attachments (wording varies by macOS version). Then wait until Window → Activity shows no more downloading — for a large mailbox this can take hours. Don't export before it's done.
Select the mailbox in the sidebar
Open Mail and click the mailbox you need — for example Inbox under the relevant account. You can Cmd-click to select several mailboxes and export them in one go.
Mailbox → Export Mailbox…
From the menu bar choose Mailbox → Export Mailbox…, then pick a destination folder (e.g. a new folder on your Desktop).
Right-click the export → Show Package Contents
The export appears as something like Inbox.mbox. It looks like a file but is a package — right-click it and choose Show Package Contents.
The real file is named just “mbox”
Inside the package sits a file named plainly mbox, with no extension. That is the actual standard-format archive — use it directly, no renaming needed. (There may also be a table_of_contents file; you can ignore it.)
Repeat for Sent — and anything else that matters
Export Sent the same way, plus Archive and any per-project mailboxes. In a dispute, what you wrote is often more important than what you received — don't leave the Sent mailbox behind.
Verify the export is complete before uploading anywhere
Check the mailbox's message count in Mail (select it — the count shows in the window) against the size of the export. Real e-mail averages tens of kilobytes per message, attachments far more — so 20,000 messages can never fit in a 9 MB file. A suspiciously small export, or one named like INBOX.partial.mbox, means Mail exported partial stubs: go back to step 1, fix the storage setting, let the download finish, and export again.
What to do with the mbox file
An mbox export is an archive, not a workspace — the next step is making it searchable so you and your attorney can filter by person, period and topic instead of scrolling through years of messages. Our guide How to organize ten years of e-mail for your lawyer walks through that stage.
You have the export — now find the evidence in it
ExhibitMail turns an mbox into a searchable, scored body of evidence: upload the file (the inner “mbox” file uploads directly — no renaming), describe the dispute, and AI ranks every message by how much it matters to your case. 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
I exported, but I only see “Inbox.mbox” — where's the file to upload?
“Inbox.mbox” is a package. Right-click it → Show Package Contents → inside is a file named just mbox with no extension. That's the one.
Why is my export tiny — a few MB for thousands of messages?
Mail exported stubs. With Limit Mail Storage / storage optimization enabled, most messages exist locally only as partial placeholders (.partial.emlx), and the export ships those — a telltale sign is an export named like INBOX.partial.mbox. Disable the storage limit (step 1 above), wait for Mail to finish downloading, then export again and re-check the size.
Do attachments come along?
Yes — messages export complete, with attachments, full headers, dates and all recipients preserved — provided they were fully downloaded before the export (step 1).
I have several accounts in Apple Mail — what should I export?
Export per account, and per mailbox within it: at minimum Inbox and Sent for every account involved in the dispute. Cmd-click selects several mailboxes for a single export run.
I already uploaded a partial export — do I have to start over?
In ExhibitMail, no: fix the export (step 1) and upload the new file. Messages are matched by their Message-ID — true duplicates are skipped, and thin partial copies are automatically replaced by the complete versions. Nothing needs deleting or undoing.
Is exporting from Apple Mail better than exporting from the provider?
Either works — the point is a complete mbox. For Gmail accounts synced in Apple Mail, Google Takeout exports straight from the server, which sidesteps any local sync gaps. For iCloud or plain IMAP accounts, Apple Mail's own export is the practical route.
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.