MailtoPst
FR
Email MBOX

Convert Email to MBOX
Online Tool

Convert email files from any format (PST, OST, OLM, EML, MSG) to MBOX. Universal conversion for Thunderbird, Gmail import, and email archiving. Works online.

Convert now → See how it works
🛡️ GDPR Compliant 🔒 TLS 1.3 Encryption 🇪🇺 Hosted in EU 🇫🇷 Built in France 🗑️ Auto-delete 24h

What is a Email file?

Email files exist in numerous formats depending on which email client or platform created them. When you need to convert email to MBOX, you may be starting from any of these source formats:

- PST (Outlook Windows) — binary database files storing emails, calendars, and contacts
- OST (Outlook Exchange cache) — local copies of Exchange/Office 365 mailboxes
- OLM (Outlook Mac) — ZIP-based archives from Outlook for macOS
- EML (individual emails) — single-email files from Thunderbird, Windows Mail, and many other clients
- MSG (Outlook messages) — proprietary Microsoft format for individual Outlook emails
- EMLX (Apple Mail) — Apple Mail's variant of the EML format

Regardless of which format your emails are in, MailtoPst can convert them to MBOX format for use with Thunderbird, Gmail import, or any MBOX-compatible application.

What is a MBOX file?

MBOX (Mailbox) is one of the oldest and most widely supported email storage formats. It concatenates multiple email messages into a single file, with each message separated by a 'From ' line. Despite its simplicity, MBOX remains a cornerstone of email interoperability.

MBOX is the native or supported format for:
- Mozilla Thunderbird — uses MBOX as its primary email storage format
- Google Takeout — Gmail exports are provided in MBOX format
- Apple Mail — can import and export MBOX files
- Unix/Linux mail systems — many Unix MTA and MDA systems use MBOX variants
- Email archiving tools — widely supported as an archival format
- Migration tools — MBOX is accepted as input by most email migration utilities

MBOX is the ideal format when you need a compact, single-file archive that can be imported into Thunderbird, uploaded to Gmail, or processed by server-side tools.

Why convert Email to MBOX?

Converting emails to MBOX format addresses many practical needs:

1. Thunderbird migration
MBOX is Thunderbird's native storage format. Converting your emails to MBOX is the most direct path to importing them into Thunderbird from any other email client.

2. Gmail import via Google Takeout compatibility
Google Takeout exports Gmail in MBOX format. By converting your emails to MBOX, you create files in the same format Google uses, making them compatible with tools designed for Gmail data.

3. Server-side email import
System administrators deploying Dovecot, Postfix, or Zimbra can import MBOX files directly using server-side tools like doveadm or mb2md. MBOX is the most commonly accepted format for server-side import.

4. Compact archival
MBOX stores thousands of emails in a single file, making it efficient for backup and archival. Unlike EML (one file per email), MBOX keeps everything in one manageable file.

5. Cross-platform data exchange
MBOX is supported on Windows, macOS, and Linux, making it the ideal format for sharing email archives between users on different operating systems.

Email vs MBOX — Key Differences

Feature Email MBOX
Compatibility Depends on source format Very broad (Thunderbird, Unix, etc.)
Storage model Varies by format All emails in one file
Openness Often proprietary Open format (RFC 4155)
Server import Limited support Widely supported (doveadm, mb2md)
File count Varies Single file per folder
Thunderbird support Varies Native format

3 methods to convert Email to MBOX

Method 1: Convert with MailtoPst (any format to MBOX)

Upload your email file (PST, OST, OLM, EML, MSG, or EMLX) to MailtoPst. Select MBOX as the output format and download the converted MBOX files, one per original folder.

Pros

  • ✓ Supports all major email formats
  • ✓ Works from any browser, any OS
  • ✓ Preserves folder structure
  • ✓ No software installation needed
  • ✓ GDPR compliant, EU servers

Cons

  • ✗ Requires internet connection
  • ✗ Paid after first conversion

Method 2: Export from Thunderbird

If your emails are already in Thunderbird, the local storage files are in MBOX format. Navigate to your Thunderbird profile folder and copy the MBOX files directly. No conversion needed.

Pros

  • ✓ Free (no tool needed)
  • ✓ Direct access to MBOX files
  • ✓ No data transformation

Cons

  • ✗ Only works for Thunderbird users
  • ✗ Requires finding profile directory
  • ✗ Not user-friendly for non-technical users
Recommended

Method 3: Google Takeout (Gmail to MBOX)

To export Gmail emails as MBOX, use Google Takeout. Select 'Mail' from the list of services, choose your export format, and Google will prepare a downloadable MBOX archive of your Gmail data.

Pros

  • ✓ Official Google tool
  • ✓ Free
  • ✓ Exports entire Gmail mailbox

Cons

  • ✗ Only works for Gmail
  • ✗ Can take hours for large mailboxes
  • ✗ Export may need multiple attempts
Try MailtoPst →

Step by step

How to convert Email to MBOX with MailtoPst

01

Upload your Email file

Drag & drop or click to upload your .email file. Files up to 51 GB supported with resumable upload.

02

Choose MBOX as output

Select MBOX from the format dropdown. MailtoPst auto-detects the best conversion settings.

03

Download your MBOX file

Conversion takes seconds. Download your .mbox file or receive it by email.

Convert your Email to MBOX now →

100 MB free credit. No credit card required.

FAQ

Frequently Asked Questions

Which email formats can I convert to MBOX?

MailtoPst converts PST, OST, OLM, EML, MSG, and EMLX files to MBOX format. This covers all major email clients including Outlook (Windows and Mac), Thunderbird, Gmail, and Apple Mail.

What is the difference between MBOX and EML?

MBOX stores multiple emails in a single file (one file per folder). EML stores one email per file. MBOX is more compact for archiving large mailboxes, while EML is better for working with individual messages. Both are open standards.

Can I import MBOX files into Gmail?

Not directly through the Gmail web interface. However, you can use Thunderbird connected to Gmail via IMAP to import MBOX files: open the MBOX in Thunderbird's local folders, then copy the emails to your Gmail account folders.

Will attachments and metadata be preserved?

Yes. MailtoPst preserves all email content during conversion, including attachments, headers, timestamps, sender/recipient information, and HTML formatting. The MBOX output is a faithful representation of the original emails.

Is the conversion secure and private?

Yes. MailtoPst processes files on EU-based servers with TLS 1.3 encryption. All uploaded and converted files are automatically deleted within 24 hours. The service is fully GDPR compliant.

Related conversions

EML → MBOX EMLX → MBOX MSG → MBOX OST → MBOX PST → MBOX
See all 30 conversion paths →

Ready to convert your emails?

First conversion free. No credit card required.

Start converting → See pricing