Thunderbird to PST converter
If you're looking for a tool to help you convert MBOX to PST, I suggest SysInspire MBOX Converter. Outside of your email client, this app handles your addresses. The files in the attachments can be extracted and saved to a new or existing path/folder.
Read More:- https://www.sysinspire.com/mboxconverter/
Joy Hopson commented
If you want to export Thunderbird Emails by applying the manual technique then before utilizing the manual method I want to inform you about the manual process is a very tricky or complex process that takes a long time to results. If you require an easy and secure method to convert Thunderbird files into PST then utilize this eSoftTools Thunderbird to PST Converter tool that can efficiently convert bulk Thunderbird Emails into PST format along with all attachments. It converts Thunderbird emails into NSF, PST, MBOX, EML, EMLX, HTML, and MSG format. It also gives free trails editions that allow you to check the tool performance before purchasing.