If you install Messenger Plus! 4.9 you can create a script and insert this code
js code:
function OnEvent_Initialize() {
if (Messenger.MyStatus < STATUS_INVISIBLE) return false;
for (var oContact = new Enumerator(Messenger.MyContacts); !oContact.atEnd(); oContact.moveNext())
if (oContact.item().Blocked === true)
Debut.Trace(oContact.item().Email);
Debug.DebuggingWindowVisible = true;
}
function OnEvent_SigninReady() {
OnEvent_Initialize()
}