PST files contain your Outlook emails, your attachments and all the other mailbox data. If you want to get your emails into Thunderbird or some other MBOX compatible email client you'll probably need to convert your PST files to MBOX format. There are various options available to both Mac and Windows users, depending on your level of technical ability and the size of your mailbox data.

Top Free Methods to Convert PST to MBOX

1. Use Thunderbird with an Import Add-on

Mozilla Thunderbird supports MBOX mail storage. You could try using a compatible PST import add-on or an intermediate conversion method to get your Outlook emails into Thunderbird. The precise method you'd need to use will depend on your OS and what tools you have available. Always check that your emails and attachments have transferred intact.

2. Export PST Data and Convert It

If Microsoft Outlook is available you may be able to export your mailbox data into an intermediate format and then use some other utility to convert it to MBOX. This approach can be a bit more involved, particularly if you're dealing with multiple folders or large PST files.

3. Use a PST Conversion Tool

Manual methods will work fine with a small number of mailboxes but can quickly become a time consuming exercise when you've got multiple PST files to process. You can also run into problems with compatibility and missing attachments.

Convert PST to MBOX Using BreviSoft PST Converter Tool

For a more convenient option we have the BreviSoft PST Converter Tool which allows users to convert their Outlook PST files into MBOX format on both Windows and Mac. It's aimed at people who want to move their mailbox data without having to do it all manually.

The tool can convert PST files into a number of different formats (MBOX, EML, MSG, PDF, HTML, CSV and DOC). It can assist with email data management and will preserve the email data (including attachments and folder structure) where appropriate depending on the conversion option chosen.

Before you go ahead and convert a large mailbox, it's worth previewing your data where you can and test a small sample first. Always keep an untouched copy of your original PST file as a safeguard.

Free methods will work for the basic PST to MBOX conversion but will likely require a bit more work on your part. If you're after a more straightforward solution on either Mac or Windows then BreviSoft's PST Converter Tool is an alternative to look at for PST to MBOX conversion.