Every Byte Matters.
PST to MBOX Converter for Outlook Mailboxes
Convert Outlook PST files to MBOX in a few clicks.
Every Microsoft Outlook PST file eventually needs to be moved when you switch to a different email client. Moving from Outlook to Thunderbird, Apple Mail, or any other open-source client requires a universally readable MBOX format. Since Outlook has no native MBOX export, you need a dedicated tool that bridges the gap without routing your private emails through a third-party server. Our software reads your local archives directly to extract the data in a single, fast pass. Keep every folder, attachment, and email property intact. Everything runs on your own computer.
Quick Summary:Convert Outlook PST files directly to MBOX for Thunderbird and Apple Mail, without requiring Microsoft Outlook to be installed.
Overview
DT PST to MBOX Converter is a desktop application that reads Outlook PST files directly and rebuilds them as MBOX files that open in Thunderbird, Apple Mail, and other MBOX-based email clients.
Outlook has no built-in option to export to MBOX. The common workarounds route your mail through Thunderbird, an add-on, or an IMAP server, one folder at a time. They are slow on large mailboxes, they can drop attachments or metadata, and some send your private email through a third-party server.
Our converter removes that middle layer. It reads the PST structure itself, so you do not need Outlook installed, you do not need an internet connection, and you do not export folder by folder. You add your files, preview the content, choose MBOX, and convert.
Key Features
Batch conversion of multiple PST files
Add several PST files, or an entire folder of them, and convert them in a single run.
No Outlook installation required
The software parses PST files on its own.
Preview before you convert
Browse folders, messages, and attachments in a structured view first.
Complete folder hierarchy preserved
Inbox, Sent Items, Drafts, Deleted Items, and every custom or nested folder keep their structure.
Attachments and embedded content intact
Attachments, inline images, and message formatting are carried into the MBOX output.
Email properties preserved
Sender, recipients (To, Cc, Bcc), date, subject, and message body are retained.
No file size limit
Convert oversized archived PST files without splitting them first.
Password-protected and damaged PST support
Open password-protected PST files and handle mildly corrupted archives.
Selective export
Convert only the folders you need, or narrow the output by date range.
Multiple output formats
Besides MBOX, export to other common formats such as PDF and EML from the same interface.
Privacy by Design: Your Mailbox Stays on Your Computer
Email is some of the most sensitive data a person or company owns. DT PST to MBOX Converter is built so that it never has to leave your machine. This makes the tool suitable for confidential client mailboxes, legal archives, and regulated environments where routing mail through a third-party service is not acceptable.
Processed locally
Conversion runs entirely on your device.
Never uploaded
We do not upload, view, or store your mail on our servers.
Works offline
No internet connection is required for conversion.
Signed application
Our Windows executables are natively compiled and cryptographically signed, so you can verify what you install.
Original PST untouched
The converter reads your source file and writes new output files, leaving the original as it was.
Why Convert PST to MBOX?
Switching to Thunderbird or Apple Mail
Bring your full history with you instead of starting empty.
Company email platform changes
Move employee archives into a format any client can read.
Client-independent backups
MBOX is an open format, so your archive is not tied to one vendor.
Retiring Outlook licenses
Convert old PST archives before decommissioning.
Legal & eDiscovery work
Provide email in a universally readable format for review.
Long-term archiving
Store mail in a format that many tools can open years from now.
How to Convert PST to MBOX in 5 Steps
Keep the original PST file untouched until you have confirmed the imported mail looks right.
Install
Install and launch DT PST to MBOX Converter on your Windows computer.
Add PST Files
Add PST files. Select a single file, several files, or a whole folder.
Preview Data
Preview your data. Check folders, emails, and attachments in the preview pane.
Choose Output
Choose MBOX as the output format and select a destination folder. Apply folder or date selection if you want a partial export.
Convert
Click Convert. When the process finishes, open the output folder and import the MBOX files into your email client.
Manual Methods vs DT PST to MBOX Converter
| Feature | Thunderbird and add-on | IMAP bridge | DT PST to MBOX Converter |
|---|---|---|---|
| Folders processed | One at a time | Drag and drop, then sync | All at once |
| Multiple PST files | Repeat the process | Repeat the process | Batch in one run |
| Large PST files | Often freezes or errors | Limited by upload speed and provider caps | No file size limit |
| Needs Outlook | Yes | Yes | No |
| Needs internet | No | Yes, upload and download | No |
| Privacy | Local | Mail passes through a third-party server | Local, offline |
| Password-protected files | Usually fails | Password must be removed first | Supported |
| Typical time | Hours | Depends on connection | Minutes |
Built for Individuals, IT Teams, and Businesses
Individuals
Individuals moving from Outlook to Thunderbird or Apple Mail who want their whole mailbox, not a partial copy.
Small Businesses
Small businesses without an IT department, changing email platforms.
IT Administrators
IT administrators converting many PST archives under deadline.
Managed Service Providers
MSPs handling several client environments and needing a repeatable, offline process.
Legal and Compliance
Legal and compliance teams who need mail in an open, readable format.
What Gets Converted
| Item | Result in MBOX |
|---|---|
| Emails from all folders | Converted with body, formatting, and headers |
| Custom and nested folders | Hierarchy preserved |
| Attachments | Preserved with the message |
| Sender and recipient fields | To, Cc, Bcc, From retained |
| Date and subject | Retained |
Technical Specifications
| Product | DT PST to MBOX Converter |
| Version | 25.7.4 |
| Input | Outlook PST files, ANSI and Unicode |
| Output | MBOX (plus other supported formats) |
| Operating system | Windows 11, Windows 10, Windows 8.1 |
| Outlook required | No |
| Internet required | No |
| Processor and RAM | 1 GHz processor, 2 GB RAM minimum |
| Free disk space | 100 MB minimum, plus room for output files |
| License | Personal, Business, and Enterprise licenses available |
How to Import the Converted MBOX Files
The converted files can be imported into Mozilla Thunderbird, Apple Mail, Postbox, SeaMonkey, Eudora, Entourage, Opera Mail, Evolution, and other clients and tools that read MBOX.
Mozilla Thunderbird: Install the ImportExportTools NG add-on, right-click a local folder, choose the import option for MBOX files, and select your converted file.
Apple Mail: In Mail, choose File, then Import Mailboxes, select the option for files in MBOX format, and pick the converted files.
After importing, spot check a few folders, open messages with attachments, and confirm dates and senders before you archive or delete the original PST.
Frequently Asked Questions
QDoes Outlook have a built-in way to export PST to MBOX?
ANo. Outlook has no native MBOX export. You either use a manual workaround through another email client or a dedicated converter such as DT PST to MBOX Converter.
QDo I need Microsoft Outlook installed to convert PST to MBOX?
ANo. The software reads PST files directly, so Outlook is not required on the computer.
QCan I convert multiple PST files at once?
AYes. Add several files or a whole folder and convert them in one batch.
QIs there a file size limit?
ANo. The converter is built to handle large and oversized PST archives without requiring you to split them first.
QWill attachments and formatting be preserved?
AYes. Attachments, inline images, formatting, and email properties are carried into the MBOX output.
QWill my folder structure stay the same?
AYes. Your Inbox, Sent Items, custom folders, and nested subfolders keep their hierarchy.
QCan I convert a password-protected PST file?
AYes, when you provide the password, the file can be opened and converted without changing the original.
QCan I convert only some folders or a date range?
AYes. You can choose specific folders and narrow the output instead of exporting the entire mailbox.
QIs it safe to use with confidential email?
AYes. Conversion happens locally on your computer, nothing is uploaded to our servers, and our Windows executables are digitally signed.
QDoes it work without an internet connection?
AYes. Conversion is fully offline.
QWhich email clients can open the converted files?
AThunderbird, Apple Mail, Postbox, SeaMonkey, Eudora, Entourage, Opera Mail, Evolution, and other MBOX-compatible clients.
QHow long does conversion take?
AIt depends on mailbox size and your hardware, but because the whole file is processed in one pass instead of folder by folder, large mailboxes typically finish in minutes rather than hours.
QCan I try it before buying?
AYes. Download the free demo, preview your data, and test the output. Purchases are also backed by a 30-day money-back guarantee.
QWhat should I do before converting?
AKeep a backup copy of the original PST file, and only remove it after you have confirmed the converted MBOX opens correctly in your new client.
Move your Outlook mailbox without losing a single email
Every purchase is covered by a 30-day money-back guarantee. We answer support emails ourselves, and we would rather you test on a real file than trust a claim. Download the free demo to load a PST file, browse the full preview, and check the converted output quality before you buy.