How to export Thunderbird for free to PST:
Open the selected mailbox by starting Mozilla Thunderbird.
Choose which emails you want to export as a PST file.
Right-click and choose "Save As" from the menu.
Click the "Select Folder" button after selecting the folder where you want to save your Thunderbird emails.
Open Microsoft Outlook and create a new folder there.
Use "drag and drop" to move the stored Thunderbird emails onto the MS Outlook interface, or import them.
When every email is shown in Outlook, choose "File" from the menu.
Choose "Open & Export," then "Import/Export," from the menu.
Click "Next" after selecting "Export to a file".
Select "Outlook Data file" now, and then click "Next" once again.
To export emails from Thunderbird to PST, choose the mailbox folder containing those emails.
To get the PST files, adjust the remaining parameters as desired and press "Finish."
It is obvious that massive mailbox migrations are not possible using the manual technique since it is time-consuming. Therefore, using a high-quality converting tool is advised for users.