When you convert PST to MBOX, retaining the original email information is important so the converted messages remain usable. A suitable conversion method should preserve the email content and attachments rather than changing or removing important mailbox data. Previewing the PST before conversion is also helpful for checking the messages and folders you plan to export.

For this PST to MBOX conversion, Aryson PST Converter  is worth considering. It supports converting PST files to MBOX while preserving email attachments and the original folder hierarchy. The preview feature allows you to check the PST mailbox data before exporting it. The tool also supports multiple PST files and does not require Microsoft Outlook to be installed. If preserving the existing email data and folder organization is your priority, it provides a practical way to convert PST to MBOX.

If you want to convert PST to MBOX while keeping the original email formatting, attachments, headers, and folder structure, you can use Advik PST to MBOX Converter .

The manual approach can be difficult, especially if you have a large PST file or don't have Outlook installed. The converter lets you add the PST file, preview the mailbox folders, select the required folders, and export them directly to MBOX format.

The basic process is:

Add your PST file to the software.
Preview the emails and select the required folders.
Choose MBOX as the export format.
Select the destination location.
Start the conversion.

The exported MBOX files can then be used with email clients such as Thunderbird, Apple Mail, or other applications that support MBOX.

For best results, use the original PST file rather than an already converted or damaged copy, as this helps preserve the available email data and formatting during conversion.