100% Private & Secure

Free MSG Converter
Convert to Any Format

Convert Outlook MSG files to EML, PDF, MBOX, CSV, HTML, JSON, or TXT.

7 output formatsOutlook MSG supportFull content extractionInstant conversion

Drop MSG file here

or click to browse

Overview

What Is MSG to MBOX Conversion?

MSG is Microsoft Outlook's native format for a single email — an OLE2/CFB (Compound File Binary) container. MBOX is a mailbox format that stores multiple messages in one file (concatenated, with From_ separators). Converting MSG to MBOX means turning one Outlook message into an MBOX file containing that single message, so you can import it into Thunderbird, Apple Mail, or other MBOX-based clients.

Our free converter processes entirely on your device. You drop one .msg file; the tool parses the OLE2 container, extracts headers and body, then writes an RFC 822-style message into MBOX format. All processing is private; nothing is uploaded.

Use MSG to MBOX for migration from Outlook to Thunderbird or Apple Mail, or for building an MBOX archive from individual MSG files. No Outlook installation is required — works on Windows, Mac, or Linux.

One MSG file yields one message in the MBOX. For many messages at once, use multiple MSG files or our PST to MBOX converter.

Features

Why use our MSG to MBOX converter

MBOX archive format

MBOX stores messages in one file (concatenated format). Used by Thunderbird, Apple Mail, and many Unix mail clients. One MSG becomes one message in the MBOX output.

OLE2/CFB parsing

Parses Outlook MSG (Compound File Binary). Extracts Subject, Sender, To, CC, body, headers and writes RFC 822-style message into MBOX.

No upload

MSG is read and converted entirely on your device. Nothing is sent to any server.

Private & secure

Your MSG file never leaves your device. Ideal for migration or backup.

How it works

How to Convert

Four steps — no install, no sign-up

Open the MSG to MBOX Converter

This page opens with MBOX already selected as the output format.

Drop your .msg file

Drag and drop one Outlook .msg file, or click to browse. File info and parsed email preview appear.

Review the message

Check From, To, Subject, Date, body snippet, and attachment count. MBOX will contain one message.

Convert & download

Click Convert & Download. Your .mbox file downloads. Import it into Thunderbird or Apple Mail if needed.

FAQ

Frequently Asked Questions

Common questions about MSG to MBOX

Q1. What is MSG to MBOX conversion?

MSG is Outlook's single-message format (OLE2/CFB). MBOX is a concatenated mailbox format (one file, many messages). Converting one MSG to MBOX produces an MBOX file containing that single message — useful for adding to an existing MBOX or starting an archive.

Q2. Why convert MSG to MBOX?

MBOX is used by Thunderbird, Apple Mail, and many Unix mail systems. Use it to migrate from Outlook to these clients or to archive messages in a standard mailbox format.

Q3. Do you upload my MSG file?

No. Conversion runs entirely on your device. Your file is read and parsed on your device. Nothing is sent to our servers.

Q4. Do I need Outlook installed?

No. The converter works on any modern platform — Windows, Mac, or Linux. No Microsoft Outlook required.

Q5. Can I add more messages to the MBOX later?

Yes. MBOX is appendable. You can convert more MSG files to MBOX and concatenate the files, or use a mail client to import additional messages.

Q6. Is the MSG to MBOX converter free?

Yes. The tool is free to use with no sign-up. Processing is fully private.

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