I do not know why that option does not appear, but you may want to read this article: http://kb.mozillazine.org/Import_.pst_files Thunderbird does not have the ability to import pst files alone, but is dependent on Outlook being installed on the same PC. I cannot give you more information than that, although if you do a web search, there are several options to convert PST to Thunderbird, such as this one: https://www.wikihow.com/Import-a-PST-File-to-Thunderbird

Ah, okey! Thought so too but...was just hoping for a simpler solution :)

Then it doesnt really matter that the alternative doesnt show up. I will check that link out thank you.

it used to be you just installed an outlook trial version.

mailstore has been suggested elsewhere as a possible solution.