'Twas brillig, and the slithy toves did gyre and gimble in the wabe

Absolutely no idea. You actually have to explicitly allow them if you're running IIS, or strange stuff happens. Found that one the hard way - had IIS locked down to local private subnet and trusted IPs on http and ftp, and blocked everything. Then wondered why if I tried to stop/restart/admin IIS it fell over and locked. I also had to kill outbound e-mail virus scanning, as that was eating the encrypted connections OE needed to talk to the uni servers.