I just installed the portable version and wanted to ad an additional language for the spell checker. However it won't work the way it is described.
However I found a very simple way, so I want to share it:
1. Download the vocabulary language with your browser. You will now have a file with exention *.xpi
2. Extract the xpi file met 7-zip
3. copy the *.dic and the *.aff file to the folder: App\Thunderbird\dictionaries\
4. start Thunderbird and you can choose between the languages when you compose a message. Nothing else to do.
would be to simply install the extension (.xpi) from the extension menu like any other extension and how all other people do it.
But well, you can do it by your complicated way as well.
Tools, Add Ons, Install from a file
so is the procedure all other people do
Yes but it did not work that way. So I decided to do it manually.
Thanks for replying.