Sarah Sweeney posted a tip to the eVolt list which I have found very helpful. One of the few annoyances I have had with Mozilla Thunderbird, my e-mail client of choice, is the fact that it doesn't include the date of the original message when replying. So, when I replied to people, it would place the text "John Doe wrote:" before their message instead of "John Doe wrote on July 28, 2004:". Sarah's tip describes how to easily modify that reply header to list whatever you so desire, all you need to do is add the following code to your user.js:
// 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 conjuction
// 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 wrote");
user_pref("mailnews.reply_header_separator", " ");
user_pref("mailnews.reply_header_ondate", "on %s");
user_pref("mailnews.reply_header_colon", ":");
// The end result will be [authorwrote][separator][ondate][colon]