If I type in a word which is not in the dictionary with "spell check as you type" enabled, and it is marked as incorrect, I can add it to the personal dictionary, and it is no longer marked as incorrectly spelt. However if later on I mistype the word even by one letter, it is marked as incorrectly spelt, but the suggested words to replace the incorrectly spelt word never include the words I have added to the personal dictionary. I have confirmed that all the words I have added are actually in my personal dictionary. I attach an example where I added the word "Angophora". Typing "Angophoora" does not bring up the suggestion "Angophora" in Thunderbird although "Angophora" can be seen to have been added in my personal dictionary. Instead it brings up a different suggested word, presumably from the dictionary I am using (English-British). This behaviour remains if Thunderbird is exited and restarted. The locale language in Thunderbird is English (Australia). The Thunderbird version is 60.8.0 (32-bit).