The spell check dialogue window has an "Edit" button. So open a Write window, provoke it to check the spelling and click this button.

When you add words, you add them to your personal dictionary; you don't alter the main dictionary file.

Thanks for the idea, Zenos - but the dialogue box doesn't have an Edit line that I can detect. See attached screen print. I'm still puzzled.

Cheers

Neil

Ah! You have right-clicked the offending word.

Try the spell check button in Thunderbird's toolbar, and you should see this:

Excellent Zenos. That worked beautifully. Thank you for the help. Cheers Neil