Apple finally posted a TechNote on this behavior HT207567 If you’re
using a network with a firewall. Make sure that you can access to the
following hosts on the corresponding ports: Server TCP Portgg.apple.com
80 and 443gnf-mdn.apple.com 443gnf-mr.ap...
This is essentially the route we went, but we integrated
theRemoveSymantecMacFiles.command into the preflight of the mpkg, and
had toadd our proxy to the postflight (Live Update doesn't play nicely
with ourproxy.pac). We had to make a minor change
to...