If you're wondering, "How do I convert PST to Thunderbird," here's a brief answer. eSoftTools PST to MBOX Converter Software is the name of the package. The files can be quickly converted using any third-party software. It's going quickly and in easy measures. The tool can transform any kind of PST file in a very short amount of time. The tool also allows the user to define a destination route for the created files. There is also a trial edition available for our new customers that helps them to upgrade PST to MBOX file format with 25 things per folder without having to pay for the full version.
Read more:- Convert PST to MBOX
Here is a best a option for you. You can try the PST to MBOX Exporter. This tool is very safe and user friendly software. Which can easily Export your thousands of big files at a time and very fast. Few weeks ago my friend also stuck in the problem of migrating big and bulk of files, but she fear of data loss, then my friend suggested her about the PST to MBOX exporter. And she got the accurate results of file. you can also download the free version of this software which exports few items from each folder. you can download this software from here:-https://www.betavare.com/pst/mbox/