Bug 1408867 - Disable preconnect (pref network.http.speculative-parallel-limit) to fix privacy issue. r=aceman

--HG--
extra : rebase_source : 115d7cd21d89a5561c17481e2bec1e7bdf296bba

mail/app/profile/all-thunderbird.js

@@ -375,6 +375,10 @@ pref("offline.download.download_messages",  0);
 // the network connection.
 pref("offline.autoDetect", true);
 
+// Disable preconnect and friends due to privacy concerns. They are not
+// sent through content policies.
+pref("network.http.speculative-parallel-limit", 0);
+
 // Expose only select protocol handlers. All others should go
 // through the external protocol handler route.
 // If you are changing this list, you may need to also consider changing the