How to open an MBOX file in Gmail — what actually works
Short version: Gmail itself can't import an .mbox file — there is no button for it. The method that works is free: import the file into Mozilla Thunderbird, connect your Gmail account over IMAP, and copy the messages across. Step-by-step below — plus what to do instead if you only need to read the mail.
Why there's no "open in Gmail" button
Gmail has no native MBOX import — not in Settings, not in Labs, not anywhere. And while Google Takeout happily exports your Gmail to .mbox, it's a one-way street: Google offers no way to push an .mbox file back into a mailbox. (Got your file from Takeout? See our Google Takeout MBOX guide.)
So "opening an MBOX file in Gmail" really means one thing: uploading the messages into a Gmail mailbox through an email client that speaks IMAP. That's what the method below does — and it's the same technique every paid "MBOX to Gmail" tool uses under the hood.
Method 1: import for real — Thunderbird + ImportExportTools NG + IMAP (free)
- Download and install Mozilla Thunderbird from thunderbird.net (free, open source).
- In Thunderbird, open Menu → Add-ons and Themes, search for "ImportExportTools NG", and install it.
- In the folder pane, right-click Local Folders and choose
ImportExportTools NG → Import mbox file → "Import directly one or more mbox files",
then select your .mbox file. It appears as a new folder under Local Folders.
Want more detail on this step? See the full Thunderbird import guide.
- Add your Gmail account: Menu → New Account → Existing Mail Account, enter your
Gmail address and sign in with Google. Thunderbird configures IMAP automatically, and your Gmail
labels show up as folders.
Tip: create a label in Gmail first — e.g. "Imported archive" — so the copied mail doesn't mix into your inbox.
- Open the imported folder under Local Folders, select the messages (Ctrl+A selects all), right-click and choose Copy To → your Gmail account → the label you picked. Use Copy, not Move — the local import stays on disk as your backup.
- Wait. IMAP uploads one message at a time, so a multi-GB archive takes hours — sometimes days. Work in batches of a few thousand messages, keep Thunderbird open and the computer awake. Original dates, senders and attachments are all preserved; Gmail files each message by its real Date header, not by upload time.
This is genuinely free — Thunderbird, the add-on and IMAP access all cost nothing. The only real cost is patience with large archives.
Privacy warning
Think twice before uploading your whole mailbox to a random "MBOX to Gmail" website. You'd be handing a stranger's server years of personal mail — password-reset links, invoices, medical appointments — and some of these sites even ask for your Google password. Every method on this page works locally on your own machine: Thunderbird reads the file from your disk, and the viewer below parses it in your browser tab. Nothing goes anywhere.
Method 2: you only wanted to read the mail — open it right here
If the goal is to see what's inside the .mbox — read messages, search them, download an attachment — you don't need Gmail at all. Drop the file below and it opens in seconds. Everything is parsed locally in your browser; the file never leaves your device.
Drag & drop your .mbox file here
or
Your file never leaves your device — everything is parsed locally in your browser.
Messages
License active ✓| # | Date | From | Subject | Size | Att. |
|---|
Message
- From
- To
- Cc
- Date
Attachments
Method 3: archive or extract instead of importing
If what you actually need is a searchable archive or evidence — not a live Gmail mailbox — importing is overkill. Two lighter options, both on this site and both processed locally:
- MBOX to PDF — merge the mailbox (or just the messages you select) into one readable PDF, for archiving or handing to a lawyer.
- MBOX to CSV — pull date / from / to / subject for every message into a spreadsheet, free.
And if your end goal is simply a better home for the mail than Gmail, the same Thunderbird import from Method 1 leaves the mailbox right there in Thunderbird — no upload needed.
Simple pricing
Viewing and CSV export are free. A one-time $9.99 unlocks PDF export forever.
Free
$0
- Open mbox files of any size
- Read every message, download attachments
- Instant search over From / To / Subject
- CSV metadata export — no account, no upload
Lifetime license
$9.99 one-time · forever
- Merged PDF export of whole mailboxes
- Scope: all, search results, or selected messages
- Pay once, use forever — no subscription
- Support a small independent tool
By purchasing you agree to the Terms of Service and Privacy Policy. Full refund within 14 days if it can't handle your file.
Frequently asked questions
Can Gmail import an .mbox file directly?
No. Gmail has no MBOX import feature anywhere in its settings, and Google Takeout only works in the other direction — it exports Gmail to MBOX but cannot import one back. The only way to get the messages into a Gmail mailbox is to upload them through an email client over IMAP, for example with Mozilla Thunderbird and the ImportExportTools NG add-on (Method 1 above).
Is the Thunderbird method really free?
Yes. Mozilla Thunderbird and the ImportExportTools NG add-on are both free and open source. The only requirement is a Gmail account — add it to Thunderbird and the Google sign-in flow enables IMAP access automatically.
How long does it take to copy a large MBOX into Gmail?
A while. Every message is uploaded one at a time over IMAP, so a multi-gigabyte archive can take many hours or even days. Copy in batches of a few thousand messages, keep Thunderbird running and the computer awake, and the transfer will finish eventually.
Will the imported emails keep their original dates and attachments?
Yes. An IMAP copy transfers the complete message, attachments included, and Gmail sorts messages by the original Date header — so imported mail lands in the right place in your timeline instead of all showing today's date.
Are online "MBOX to Gmail" converter sites safe?
Be careful. Such sites ask you to upload your entire mailbox — years of personal mail, password-reset links and invoices — to a stranger's server, and some even ask for your Google password. Prefer tools that work locally: Thunderbird, or the viewer on this page, which parses the file in your browser and never uploads it.