How to Migrate MBOX to PST — Thunderbird to Outlook

MBOX vs PST: What Is the Difference?

MBOX is a plain-text file format that stores multiple email messages sequentially in a single file. Mozilla Thunderbird, Apple Mail, Eudora, SeaMonkey, and many Unix-based mail servers use MBOX as their default storage format. Each Thunderbird folder (Inbox, Sent, Drafts) is saved as a separate MBOX file inside your profile directory.

PST (Personal Storage Table) is a binary format developed by Microsoft for Outlook. A PST file contains emails, contacts, calendar entries, and tasks in a structured database. Outlook versions 2007 through 2024 use the Unicode PST format, which supports files up to 50 GB.

The two formats are fundamentally incompatible. You cannot open an MBOX file directly in Outlook, and Thunderbird cannot read PST files. A dedicated converter is needed to transform one format into the other.

Step-by-Step: Convert MBOX to PST

• Step 1. Launch Total Thunderbird Converter Pro. The program detects your Thunderbird profile automatically and displays all mail folders in a tree view.
• Step 2. Select the folders you want to migrate. Use Check All to export everything at once, or pick individual folders.
• Step 3. Click the PST icon in the format toolbar at the top of the window.
• Step 4. Choose a destination folder for the output PST file.
• Step 5. Set a file-name template if you want multiple PST files (one per folder) or leave the default for a single combined PST.
• Step 6. Press Start. The converter creates a PST file that preserves folder structure, sender/recipient data, dates, and all attachments.

When the conversion finishes, open Outlook and use File → Open & Export → Import/Export to import the PST file. Your messages will appear with the original folder hierarchy intact.

Alternative: Manual Migration via IMAP

There is a free manual method: create a Gmail or IMAP account, connect it to both Thunderbird and Outlook, drag your emails to the IMAP folder, then sync them down in Outlook and save to a local PST. However, this approach has serious drawbacks:

• Extremely slow for large mailboxes (thousands of emails take hours or days).
• Attachments may get stripped or corrupted during IMAP sync.
• Folder structure is often lost or flattened.
• Requires an active internet connection and a third-party IMAP account.

A dedicated converter finishes the same job in minutes, offline, with guaranteed data integrity.

Why Use Total Thunderbird Converter Pro?

No Outlook installation required. The converter creates valid PST files independently using its own PST engine. You can run the conversion on any Windows PC, then transfer the PST to the target machine where Outlook is installed.

Preserves attachments. Every attachment is stored inside the PST exactly as it was in the original MBOX — no data loss, no re-encoding.

Batch processing. Migrate hundreds of thousands of emails in one session. The program handles large mailboxes (10 GB+) efficiently without running out of memory.

Apple Mail & other clients. The MBOX format is also used by Apple Mail, Eudora, Postbox, and SeaMonkey. Use Open Mailbox to import any MBOX file, not just Thunderbird profiles.

Multiple output formats. Besides PST, you can export the same emails to PDF, DOC, HTML, TIFF, TXT, or EML for archiving, e-discovery, or compliance purposes.

Command-line support. Automate MBOX-to-PST migration in scripts and scheduled tasks using the built-in command-line interface.

MBOX to PST: Manual vs Converter

MBOX to PST Conversion: FAQ ▼