MBOX to Outlook Converter Software: Convert MBOX to PST, Free Download

How to download and use MBOX to Outlook Converter Software

Collect your MBOX files

Thunderbird keeps each folder as a separate mbox file with no extension, inside Profiles\\.default-release in your Thunderbird data folder. Apple Mail exports a mailbox as a .mbox package. Eudora uses .mbx mailboxes; old Unix mail uses plain spool files. Drop the files you want to convert into the file list. MBOX to Outlook Converter Software takes many at once. Need your mail in Gmail? You can import MBOX to Gmail.

Choose one PST or one per mailbox

Merge into one PST is off by default, which gives you one PST per input file. If you want everything in a single file instead, tick it before you start.

Run the conversion

Start the run and let it work. Several gigabytes of mail with attachments will take time to convert.

Import the PST into Outlook

In Outlook, go to File > Open & Export > Import/Export > Import from another program or file > Outlook Data File (.pst). Select the PST you made and choose where to import it. Your folder tree appears with the original dates and senders intact.

Built for stacks of mailboxes

Inherited a colleague's 6 GB Thunderbird profile? Add the whole pile at once: thirty-odd folders, each a separate file with no extension, nested in .sbd directories. The program treats each file as its own mailbox and carries the folder names over into Outlook.
One PST, or one per source

Tick Merge into one PST to put every source in its own top-level folder within a single PST. Two mailboxes both named Inbox stay separate. This suits one person's mail split across several mbox files; for per-user archives, leave the checkbox off to keep the output separate.

Byte for byte, checked in Outlook

Headers and bodies carry over byte for byte, including the subject, sender line and original send date. You keep HTML formatting, plain-text alternatives, read/unread flags and attachments as real attachments. We export the written PST back out and compare it with the source, then mount it in a real Outlook 2016 to check the folder tree.
Unicode PST output

You get a PST in the modern Unicode format that desktop Outlook has used since 2003. It opens in everything from Outlook 2010 to Microsoft 365. Legacy ANSI PST files stop at 2,075,149,312 bytes (about 1.93 GB), a limit that ten years of mail with attachments can easily exceed.

Outlook does not have to be installed

We built the program to write the PST itself, so Outlook can be closed or absent from the converting PC. .NET Framework 4.x already ships with Windows 10 and 11, with no extra runtime to install. You can convert on one workstation and pass the PST to the person who uses Outlook.
Test MBOX to Outlook Converter on your own archive

The trial converts only a part of each mailbox. Open the result in Outlook to check your folders, dates and attachments before you commit to converting the full archive. If your export contains separate .eml messages rather than one mbox container, see how to convert individual eml files to outlook pst.

Which MBOX files it reads

MBOX is a plain-text container, standardized as RFC 4155 in 2005. Each message starts with a From line, one message after another. This shared layout lets MBOX to Outlook Converter read mailboxes from clients that never talked to each other.

Source	What the files look like	Notes
Mozilla Thunderbird	One mbox file per folder, no file extension; subfolders in .sbd directories	Stored under Mail and ImapMail in your Thunderbird profile.
Eudora	.mbx mailbox files	The same mbox layout under a different extension.
Unix mail, Pine, mutt	Plain mbox spool files	The original RFC 4155 shape. Old server archives usually land here.
Postbox	Thunderbird-style mbox files	Postbox is built on the same storage layout, so its mailboxes read the same way.
Apple Mail export	.mbox package: a folder holding the mbox data file, Info.plist and an Attachments directory	Point the program at the mbox data file inside the package. To get mail straight from a Mac library rather than an export, see apple mail export to outlook pst.

Download for Free

Who uses MBOX to Outlook Converter Software

You switched clients

Your new job comes with a new laptop and Outlook, while ten years of your mail sits in a Thunderbird profile or an old Apple Mail export. Bring that archive into Outlook so you can search it there.

You are the admin running the migration

Your department is moving from Thunderbird to Exchange and Outlook, and you have a share full of mbox exports, one folder per person. Convert them in a batch with a separate PST per user. If your destination is a Microsoft 365 mailbox, you can import an MBOX file into Microsoft 365 directly from the same exports.

You handle records or discovery

A litigation hold or records request sends you back to an old Thunderbird profile or mailbox export, and your reviewers use Outlook. You need to convert privileged mail on your own hardware: uploading it to a website that converts files in the cloud is off the table.

MBOX to PST Converter Software for Outlook

Price

from $ 29.99

Version

1.5

File Size

9 Mb

Last updated on

13/07/26

System Requirements

Windows 11/10/8.1/8/7 (32/64 bit)
Intel i3, AMD Ryzen 5 or above
4 GB of RAM or above
NVIDIA® GeForce® series 8 and 8M, Intel® HD Graphics 2000, Quadro FX 4800, Quadro FX 5600, AMD Radeon™ R600, Mobility Radeon™ HD 4330, Mobility FirePro™ series, Radeon™ R5 M230 or higher graphics card with up-to-date drivers
1280 × 768 screen resolution, 32-bit color
1 GB of free hard disk space or above

Frequently Asked Questions

Can Outlook open MBOX files?

No version of Outlook has an MBOX reader. Its Import/Export wizard accepts Outlook data files and comma-separated contact lists, with calendar files under a separate entry. MBOX originated on Unix and in Mozilla clients; Outlook stores mail in its own container. The supported path is to convert mbox to PST.

Can I import MBOX into Outlook without a converter?

Add the same account to both clients over IMAP and let the server sync the mail across. Or export each Thunderbird message as .eml and drag the files into an Outlook folder. Drag-and-drop is manageable for twenty messages; twenty thousand is another matter. Read and unread state gets mangled along the way, and dragging thirty folders by hand at 11 pm is a chore. If your mail still sits only on an IMAP server, email backup software that copies an IMAP mailbox to PST produces the PST directly, without the Thunderbird step.

What program can open MBOX files on Windows?

Thunderbird can open it if you copy the file into a profile folder. For another program, convert the mailbox to a format it reads: PST for Outlook, or PDF for a fixed, printable archive. Use a separate program to archive an mbox mailbox as pdf. Notepad can also open an mbox, though you will see the raw source, including base64 attachment blobs.

How do I import Gmail Takeout (MBOX) into Outlook?

Google Takeout exports Gmail as .mbox, never PST, and can take hours or days to build the export. Unzip the archive to find one large .mbox file per account or label. You will need to convert it before opening it in Outlook. We have tested Thunderbird, Eudora and Postbox as sources, along with Unix mail spools and Apple Mail exports. Takeout uses the same plain-text container, but we have not certified it as a source. Run your Takeout file through the trial and check the result before relying on it.

How do I open Thunderbird mail in Outlook?

In Thunderbird, find your profile path under Help > Troubleshooting Information. Inside Mail or ImapMail, the files named Inbox, Sent, Archives have no extension. These are your mailboxes: convert them to PST and import the PST in Outlook. Subfolders are separate files in the matching .sbd directory. Add those files to the list too, or their mail will be left out.

Can I export emails from Thunderbird myself?

Yes. The ImportExportTools NG add-on exports a folder as mbox or individual EML files from the right-click menu. You can also skip the add-on: the mbox files are already in your profile on disk. Copy them out of the profile folder and open them in MBOX to Outlook Converter Software.

Can I add my Apple Mail archive to Outlook?

Yes, if you exported it from Mail as a .mbox. On macOS, a .mbox is a package that Finder displays as a single file. Open it to find a data file, a plist and an Attachments folder. Copy the whole package to Windows and point the MBOX to Outlook Converter download at the data file.

Can I edit or fix an MBOX file directly?

You can open it in a text editor: it is plain text, with messages separated by a From line as RFC 4155 describes. Be careful with edits. Headers, MIME boundaries and base64 attachments must stay consistent; one stray line break can orphan every message after it. To keep some folders and drop others, select the files you want and leave their contents alone.

Will attachments, folders and dates survive the conversion?

Yes. A naive import copies message text and drops the MIME parts, leaving attachments stranded in the raw source as encoded text. That causes the attachment loss often reported on mail forums. The program rebuilds every message inside the PST with its parts intact. Your attachments arrive as files you can double-click.

Is there a size limit for the PST file it creates?

50 GB. Outlook 2010, 2013 and 2016 cap Unicode PST files at 51,200 MB (the MaxLargeFileSize default). Outlook 2007 and 2003 cap them at 20,480 MB. The legacy ANSI format stops at 2,075,149,312 bytes, about 1.93 GB. At the limit, Outlook refuses to add items and reports that the file has reached its maximum size. For an enormous archive, convert its mailboxes into separate PST files instead of merging them into one.

Do I need Outlook installed to run the conversion?

No. You can convert on a PC without Outlook installed or open. You need Outlook only on the machine where you will read the mail, to import the finished PST file.

Download MBOX to Outlook Converter Software for Windows 10, 11