Thunderbird checks an email you are composing for the word "attached" and if it finds it, warns you that you may have forgotten to attach a file. Can I add the word "stegys" as a synonym for "attached" ? This is the Cornish word for attached. Alternatively, if I add the Thunderbird Cornish dictionary, would Thunderbird warn me when it finds "stegys" in the text. I already have an excellent Cornish dictionary extension for Libre Office, and as such it seems overkill to add a second dictionary as I can spell check text in Writer and then paste it into Thunderbird. So adding a synonym would be my preferred option. Many thanks in advance.