I've just been down the same path discussed in this thread and I'd love to know the magic to make it work. As far as I can see, the issue really is totally on the PC side, likely in the underlying Microsoft SQL environment. I've set up packet logging on my router and UltraMail doesn't appear to ever get to the point where a TCP/IP packet gets sent from the PC. The VM card responds to pings from the same PC as well.
Email or PM me if you want/need more details.
