Ok, had a real oddity here, and am working to track it down.

I've done a few updates to 7(1708) via CR at this point, and hadn't had any real issues, so during a slack time today updated our email server.  Now, prior to the update, I had our email server set up with postfix, but after the update the system had sendmail enabled and postfix disabled.  Like I said, I'm still looking into it, but just a heads-up.

A 'systemctl disable sendmail; systemctl stop sendmail' then 'systemctl enabled postfix; systemctl start postfix' seems to have restored things.  I would probably be well-off to remove sendmail altogether, but I would have thought that the startup settings would have been honored anyway.