diff --git a/mozilla/mailnews/mailnews.js b/mozilla/mailnews/mailnews.js
index 09c0bbeb0c6..9786a4501d3 100644
--- a/mozilla/mailnews/mailnews.js
+++ b/mozilla/mailnews/mailnews.js
@@ -79,6 +79,7 @@ pref("mail.use_altmail",                    false);
 pref("mail.altmail_dll",                    "postal32.dll");
 pref("mail.use_altmail_for_news",           true);
 pref("mail.thread_mail",                    false);
+pref("mail.thread_without_re",				true);
 pref("mail.sort_mail",                      false);
 pref("mail.ascend_mail",                    false);
 pref("mail.leave_on_server",                false);
diff --git a/mozilla/modules/libpref/src/init/mailnews.js b/mozilla/modules/libpref/src/init/mailnews.js
index 09c0bbeb0c6..9786a4501d3 100644
--- a/mozilla/modules/libpref/src/init/mailnews.js
+++ b/mozilla/modules/libpref/src/init/mailnews.js
@@ -79,6 +79,7 @@ pref("mail.use_altmail",                    false);
 pref("mail.altmail_dll",                    "postal32.dll");
 pref("mail.use_altmail_for_news",           true);
 pref("mail.thread_mail",                    false);
+pref("mail.thread_without_re",				true);
 pref("mail.sort_mail",                      false);
 pref("mail.ascend_mail",                    false);
 pref("mail.leave_on_server",                false);