diff --git a/mozilla/mail/app/profile/mailnews.js b/mozilla/mail/app/profile/mailnews.js
index cec9a105b8e..5190da91c5e 100644
--- a/mozilla/mail/app/profile/mailnews.js
+++ b/mozilla/mail/app/profile/mailnews.js
@@ -352,7 +352,8 @@ pref("mail.server.default.delete_model", 1);
 pref("mail.server.default.fetch_by_chunks", true);
 pref("mail.server.default.mime_parts_on_demand", true);
 
-pref("mail.server.default.always_authenticate",false);
+pref("mail.server.default.always_authenticate",false);
+pref("mail.server.default.singleSignon", true);
 pref("mail.server.default.max_articles", 500);
 pref("mail.server.default.notify.on", true);
 pref("mail.server.default.mark_old_read", false);