I use this method to get a word count when composing emails. Make Hidden files and folder visible: * http://kb.mozillazine.org/Show_hidden_files_and_folders In Thunderbird: * Help > Troubleshooting Information * click on 'show folder' button * a new window opens showing your Profile folder. * '''Close Thunderbird now - this is important. ''' * Create new folder and call it '''chrome''' note the spelling - use a lower case 'c' It should be in the same place as the 'Mail' folder. see image below. * open Notepad: usually located under 'All Programs' > 'Accessories' > 'Notepad' Go to this link and section 'Word Count' * http://kb.mozillazine.org/UserChrome.js/Mail#Word_count * Copy paste the code into 'Notepad' and save as '''userChrome.js''' (note the spelling - capital 'C') in the '''chrome''' folder. Go to this link: * http://downloads.mozdev.org/userchromejs/ * Use drag and drop to copy the 'userchromejs-2.0-sm+tb+fx.xpi' file to your computers 'Downloads' folder or the desktop. * Start Thunderbird * 'Menu icon' > 'Add-ons' * select 'Extensions' * click on gear wheel icon and select 'Install addon from file' see second image below * locate the *.xpi file you copy pasted into eg: 'Downloads' folder. * click on 'Open' * Once addon extension is installed, at prompt, Restart Thunderbird. * click on 'Write' * Type some content. * Highlight the typed words to see number in bottom left Status bar.

Believe it or not, the old mailtweak add-on still does this in Earlybird (TB 53): http://mailtweak.mozdev.org/tweaks.html#wordcount Not all tweaks still work, but many do. Installation may be easier if you first install [https://addons.mozilla.org/en-US/thunderbird/addon/checkcompatibility/ this add-on].