The simplest and most secure solution for converting MBOX files to PST is the BLR Tools MBOX to PST Converter tool. Although manual techniques, such as combining Thunderbird and Outlook, can be effective, they are time-consuming, necessitate technical setup, and frequently result in the loss of formatting or attachments. Multiple MBOX files can be converted into Outlook PST files in bulk using BLR MBOX to PST Converter, preserving email attributes such as subject lines, sender/receiver information, attachments, and folder structure. The majority of tools also let you preview emails before conversion, filter emails by date range, and split large PST files.  
 
This method eliminates the trouble of importing through several email clients and is significantly faster. A professional MBOX to PST converter is worthwhile if accuracy and efficiency are your main concerns.