As new mailbox servers are added to the org, they will be picked up when the servicelet runs and be added to the key. So, the other part of what the RpcHttpConfigurator servicelet does it that is queries the AD for all mailbox servers and stamps them in the ValidPorts regkey allowing access to ports 6001, 6002, 6004 for both FQDN and Netbios access. This list is maintained through the HKEY_LOCAL_MACHINE\Software\Microsoft\Rpc\RpcProxy\ValidPorts regkey and contains all the servers/ports that RPCProxy is allowed to talk to. Ouch ! To alleviate this problem, RPCProxy only allows connections to be made to servers and ports that are in a trusted list.
By the weakest link theory, all you'd need to do would be hack into a single IIS server and you'd have free access to all servers in the org. But imagine if you were able to connect to any server in the organization if you were able to auth against an IIS box running RPCProxy. RPCProxy is an ISAPI extension that unmarshals the RPC packet, retrieves the RPC endpoint that the client wants to talk to and forwards the packet to the endpoint. A client side RPC component is responsible for marshalling every RPC packet into an HTTP tunnel and sending it over to the \rpc vdir on the CAS server.
Outlook Anywhere depends on the RPC/HTTP Windows component to do the marshalling and unmarshalling of the RPC packets from the client to the CAS server. Ok, so that's just part of what the servicelet does. This means that if you manually change the settings on this vdir, you should expect to be run over pretty shortly by the RpcHttpConfigurator (unless you have set the reg key to 0). When the RpcHttpConfigurator runs, it picks up the IISAuthenticationMethods and SSLOffloading values from the AD and stamps it on the \rpc vdir settings in the IIS metabase - overwriting any previously set value. Note that setting this value to 0 turns off the RpcHttpConfigurator. This servicelet runs every 15 mins by default, but the interval can be adjusted by changing the value of the HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeServiceHost\RpcHttpConfigurator\PeriodicPollingMinutes regkey.
Server facing properties are picked up by a servicelet called RpcHttpConfigurator which runs as part of the Microsoft Exchange Service Host service. Client facing properties are picked up by Autodiscover and supplied to Outlook to configure client access to the Outlook Anywhere service. Examples of Server facing properties are IISAuthenticationMethods, SSLOffloading. Examples of client facing properties are ClientAuthenticationMethod, External Host Name. The values that you provide to Outlook Anywhere settings can be classified into 2 types of properties - client facing and server facing.
Instead, let's do a slightly deeper dive than the cmdlet documentation provides. There is already a bunch of documentation on it. How does Outlook Anywhere work? I won't cover details on the cmdlets that enable and change settings for Outlook Anywhere. Given how long this blog post is overdue, I plan to cover a lot of topics, from frequently asked questions to common misconceptions to problems with Outlook Anywhere to suggested solutions for different problems. Somehow, I keep getting myself caught up in one thing or another, and have consequently delayed writing this blog post by almost 4 months. It's been a while since I've been thinking of writing a blog post about various aspects of Outlook Anywhere that people have been asking questions about. EDIT : Corrected a typo in a "DisabledComponents" registry key name.