Hello Ron,

I have to admit it: this is one of the shortcomings of the Ironport interfaces.
If you know where to look, you can find it, but it's certainly not as obvious as most other parts of the interfaces.

Now, how to do it:
If you log on to the web interface you can select "Monitor" and then "Delivery status".
If you then click on the "Latest Host Status" column header the list will be sorted based on that field, by default you get the hosts that are down on the top. (you might need to raise the “Items Displayed” selector)
If you then select one of the host lines you can see the details for that target. The number of "active recipients" indicates the number of recipients on that specific target that are still in the queue. This is not necessarily the same as the number of messages since one message can be targeted to multiple recipients on the same domain (or host).

Please note that in most cases these unreachable destinations are not willing to accept mail at all.

If you have a case where you want to force the MTA to start-up the delivery right away (for instance if one of your own systems was down and now available again) you need to go to the CLI and enter the "deliver now" command, select option "1" (the default, "By recipient host") and enter the name of the recipient host as found in the "delivery status" window.

If you want to monitor the status of a specific host in semi real-time you can use the CLI command "hostrate".

Hope this helps.

Steven