diff --git a/mailnews/mailnews.js b/mailnews/mailnews.js
index ed661b01f7..d663877d47 100644
--- a/mailnews/mailnews.js
+++ b/mailnews/mailnews.js
@@ -635,7 +635,7 @@ pref("mail.biff.show_balloon", false);
 #elifdef XP_MACOSX
 pref("mail.biff.animate_dock_icon", false);
 #elifdef XP_UNIX
-pref("mail.biff.use_system_alert", true);
+pref("mail.biff.use_system_alert", false);
 #endif
 
 // add jitter to biff interval