In short, RPC Proxy, and IPv6 on Windows server 2008 has some “issues”.
This only occurs when you have Exchange installed on Windows 2008, not Windows 2003.
This also only applies to a "all roles installed on same server”. For my situation, this was a single exchange server installation.
The rpc proxy component is not compatible with IPv6, and even if you have it disabled (uncheck the ipv6 on the nic settings), it still uses the loopback component.
From the msexchange.org team, we find this:
If you’re in a single-server scenario where the RPCProxy and Mailbox are on the same machine, then the above does not work since the loopback interface still uses IPv6. In this case, you need to make the following changes in the system32\drivers\etc\hosts file:
- Comment out the line ":::1 localhost"
- Add the following two lines:
<IPv4 address> <hostname of the computer>
<IPv4 address> <FQDN of the computer>
When I tried the “rpcping” command (see the above link for how to), on port 6004, it gave me an error of Exception 1722 Port 6001 and 6002 worked ok. It is normal for the command to ask you passwords twice, and you can’t mess up and use the backspace key. You have to type it correct both times.
Also I noticed that the rpc proxy ports were wrong in the registry. The Valid Ports entry was set to servername:593;servername:49152-65535 instead of
Honestly, I don’t know if those registry settings were bad or not, but I changed them to 6001-6002 and 6004.
I also tried uninstalling rpc over http, reboot server, and reinstalling rpc over http, but that did not fix it.
And to clarify, I do have Exchange 2007, sp1, with rollup 5 installed. And Windows 2008 with SP1.