How to convert PST to Thunderbird without outlook?
If someone knows about “PST to Thunderbird without outlook”. I have a realistic solution of PST to Thunderbird without Outlook conversion problems that name eSoftTools PST to MBOX Converter software. It's simple to complete only and takes a few more steps. A PST file's folders should be exported as separate MBOX files. A trial edition is also available for all of our users. In the demo version, you can convert up to 25 email objects per folder without paying anything.
More information:- https://www.esofttools.com/pst-to-mbox-converter.html

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ChrisTwitty commented
In case you require the conversion of PST to Thunderbird without actually installing Outlook, you have to use a PST converter tool, as it is the best option. These are programs that change PST directly to MBOX format, which is compatible with Thunderbird. Just find reputable PST converting software, such as that provided by BLR Tools, and put the PST file up there. The program enables you to view your emails and then translate them to MBOX regardless of Outlook. When the conversion is complete, you will be able to import the MBOX file into Thunderbird with the help of the Import Export Tools NG add-on. It is a simple, no-nonsense method to view your Outlook mail in Thunderbird.
Click here: https://www.blrtools.com/pst-exporter-tool.html