What is an MBOX file?
MBOX is the oldest email storage format still in everyday use: an entire mail folder stored as one plain-text file, with each message introduced by a From_ separator line (literally From followed by the sender and a timestamp). Thunderbird stores folders this way, Apple Mail exports mailboxes as .mbox, and — the reason most people meet the format today — Google Takeout delivers your entire Gmail history as one giant .mbox file. For the full anatomy of the format, read What is an MBOX file? in the Learn section.
Why convert an MBOX file to CSV or Excel?
An .mbox archive is write-only in practice — without importing it into Thunderbird or another mail client, you can't answer even simple questions about it: how many messages are in here, from whom, over what date range, with which attachments? A CSV index answers all of that in a spreadsheet: sort by sender for a cleanup or an unsubscribe pass, filter by date for a records request or legal hold, pivot on attachment names to find every invoice, or use Message-IDs to dedupe overlapping exports. The step-by-step workflow is in How to convert MBOX to CSV.
What ends up in each column
- Date: The Date header, normalized to YYYY-MM-DD HH:MM (UTC) whenever it parses.
- From / To / Cc: Sender and recipients, with encoded international names decoded.
- Subject: Decoded from RFC 2047 =?UTF-8?B?...?= syntax when needed.
- Message-ID: The globally unique ID — what reply chains and dedupe scripts key on.
- Attachments / Attachment Names: How many attachment parts each message carries, and their filenames.
- Size (KB): The size of each raw message block inside the mailbox.
The converter handles the format's sharp edges for you: folded (wrapped) header lines are rejoined, quoted >From lines inside bodies aren't mistaken for message boundaries, and RFC 2047 encoded-words in subjects and names are decoded from both their base64 and quoted-printable forms.
How to convert MBOX to CSV
- Drop your .mbox file above (Google Takeout, Thunderbird, and Apple Mail exports all work). Parsing happens on your device — the mailbox is never uploaded.
- Check the summary: total messages, date range, unique senders, and how many messages carry attachments.
- Preview the index — one row per message, bodies left safely in the archive.
- Export as CSV for Excel, XLSX, or JSON.
Troubleshooting MBOX files
Why doesn't the CSV contain the message bodies?
This tool builds an index of the mailbox, not a full export: one row per message with its Date, From, To, Cc, Subject, Message-ID, attachment count and names, and size. That's what a spreadsheet is actually good at — searching, sorting, filtering, and counting thousands of messages. Full bodies are often multi-part MIME with HTML and base64 blocks that would make the CSV unusable; the bodies stay safely in your .mbox file.
How do I get an MBOX file out of Gmail with Google Takeout?
Go to takeout.google.com, deselect everything except Mail, and export. Google delivers a .zip (or .tgz) containing one or more .mbox files — typically "All mail Including Spam and Trash.mbox", or one file per label if you narrowed the export. Unzip it and drop the .mbox file into the converter above; nothing is uploaded, so even a large personal archive stays on your device.
What were those =?UTF-8?B?...?= codes in my subject lines?
That's RFC 2047 encoded-word syntax — email headers are ASCII-only by rule, so any subject or name with accents, non-Latin characters, or emoji gets wrapped as =?charset?B?base64?= or =?charset?Q?quoted-printable?=. This converter decodes both encodings (UTF-8 and Latin-1 charsets) automatically, so the CSV shows "Résumé 🎉" instead of the raw encoded gibberish.
Is this MBOX converter really free?
Yes — every mailbox parses and previews free with no signup and no upload. Free exports include the first 100 messages; a one-time $19 license unlocks unlimited exports on every LegacyFile tool.
Related conversions
Migrating more than mail out of an old account or machine? The VCF to CSV converter does the same job for exported contacts — Google Takeout typically hands you a .vcf address book right next to the .mbox mailbox.