Charamel/Silvermel for Firefox/Thunderbird 24 or up
Install the " Disable Add-on Compatibility Checks " plugin to skip the plugin compatibility check. Then you can install and use the Charamel/Thunderbird plugin even though it is yet compatible with Firefox/Thunderbird 24 or up. Firefox: https://addons.mozilla.org/en-US/firefox/addon/checkcompatibility/ Thunderbird: https://addons.mozilla.org/en-us/thunderbird/addon/checkcompatibility/