I moved to http://quickquote.mozdev.org/faq.html instead of playing around with user.js everytime for thunderbird reply message customization. I would have done the good old days" //vista: C:\Program Files\Mozilla Thunderbird\defaults\user.js (ofcourse you need to change permissions to edit..) // Change the reply header // 0 - No Reply-Text // 1 - "[Author] wrote:" // 2 - "On [date] [author] wrote:" // 3 - User-defined reply header. Use the prefs below in conjunction with this: user_pref("mailnews.reply_header_type", 3); // If you set 3 for the pref above then you may set the following prefs. user_pref("mailnews.reply_header_authorwrote", "%s said the following"); user_pref("mailnews.reply_header_ondate", "on %s"); user_pref("mailnews.reply_header_separator", " "); user_pref("mailnews.reply_header_colon", ":"); // The end result will be [authorwrote][separator][ondate][co...