A while back I set up a few external domains for GWMonitor to use as logging and performance testing. (it sends the gwia log to that external domain .. or something..)
The whole setup is a bit sketchy but it seems to have stopped working at some point in the past but I only just noticed it after installing gw14Sp2 as we don't check it that often.
From what I can tell an external domain is just a virtual entity with no active MTA so I'm not entirely sure why it isn't working. A 2nd external domain is listed as open. I'm just not sure how it is supposed to work with GWMon using it. It closes the domain because there is obviously nothing listening on the designated port, or should external domains be pointing to the normal MTA port ?
We only have a single MTA/POA setup for roughly 250 users so I never really tinkered with multiple domains.