So, you are a savvy Exchange administrator with a proactive monitoring tool and you are notified that your Submission queue on one of your Exchange servers has a high quantity of messages in the queue.

What do you do?

First, you will want to check the submission queue

  • Open the Exchange Management Console and click Toolbox
  • Then Choose Queue Viewer


  • Notice there are 247 messages in the submission queue in this case, but there could be any quantity here.


  • Double-click on the submission queue and notice that the messages likely are similar with the following detail:

From Address: <>

Status: Retry

Last Error: 420 4.2.0 RESOLVER.ADR.Ambiguous; ambiguous address




The submission queue can become backlogged for several reasons. For example, there could be a message in the queue with a bad header or alerting was enabled for a third-party application that caused an arbitrary loop. In either case, take the time to research and track down the root cause.

Resolution options

  • Go to Start, Control Panel, Administrative Tools
  • Double-click Services
  • Restart the Microsoft Exchange Transport Service


If this doesn’t resolve your issue

  • Open Exchange Management Shell
  • Type Get-Message -Filter {FromAddress -eq “<>”} -Server hubtransportserver | Remove-Message and press Enter
  • Choose A to select Yes to All


This article applies to Exchange 2010