User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:5.0.1) Gecko/20100101 Firefox/5.0.1 Build ID: 20110707182747 Steps to reproduce: Installed Enigmail Configured user_pref("mailnews.send_plaintext_flowed", true); in user.js Started Thunderbird and composed a message Actual results: Message had format=flowed DISABLED Expected results: format=flowed should have been ENABLED It worked in TB 3.1.11. The Enigmail extension sets format=flowed disabled via a .js configuration, so it seems that the order of configuration directives has changed. While in TB 3.1.11, user.js overwrote the extension, it seems to be the other way round now, effectively making it impossible to supersede a configuration directive by an extension

I should add that in the Enigmail Xpi this line is part of to defaults/preferences/enigmail.js: pref("mailnews.send_plaintext_flowed", false);

This behaviour persists in TB 6.0.