Bug #363993 --> ModifyCard is not a property of nsIAbMDBDirectory, it is a property of nsIAbDirectory. sr=bienvenu

mail/base/content/mailWindowOverlay.js

@@ -2345,7 +2345,7 @@ function allowRemoteContentForSender()
   }
 
   var allowRemoteContent = false;
-  if (cardForEmailAddress)
+  if (cardForEmailAddress && addrbook instanceof Components.interfaces.nsIAbDirectory)
   {
     // set the property for remote content
     cardForEmailAddress.allowRemoteContent = true;