Bug 3253776 --> Get New Mail for the RSS account fails if chosen from the get new mail toolbar button drop down.

If the server doesn't have an inbox to ask for new mail, just pass in the root folder and let the incoming server figure it out.

mail/base/content/mailWindowOverlay.js

@@ -709,9 +709,12 @@ function GetInboxFolder(server)
 
 function GetMessagesForInboxOnServer(server)
 {
-  dump ("GetMessagesForInboxOnServer uri = " + server.serverURI + "\n");
   var inboxFolder = GetInboxFolder(server);
-  if (!inboxFolder) return;
+
+  // if the server doesn't support an inbox it could be an RSS server or some other server type..
+  // just use the root folder and the server implementation can figure out what to do.
+  if (!inboxFolder)
+    inboxFolder = server.rootFolder;    
 
   var folders = new Array(1);
   folders[0] = inboxFolder;