At least sometimes, when our Exchange server gets rebooted for whatever reason, the ValidPorts data at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\RpcProxy resets to using only the bare machine name and the FQDN for the local domain, but loses the additional outside domain information added so that outlook-anywhere will work by accessing the external domain name.

I'm not sure what's causing this issue, and my google-fu is failing to find anything useful so far.

I could, as a workaround, use a script to make sure that the data for the key/value is correct whenever the server starts up, but that doesn't get to the root of the issue and could have unintended consequences.

The computer is running Windows Server 2008 R2 and Exchange 2007 SP3

EDIT: I just edited this key a few hours ago and came back to the server to see that it had changed WITHOUT a reboot or any software/patches being installed. I'm looking through scheduled tasks and RSOP now for clues.

EDIT: I don't see anything in RSOP or Tasks that points to why this key keeps reverting. Logoff/logon doesn't seem to be the cause either.

EDIT: Triple checking my settings: Outlook Anywhere was initially configured using the Exchange Management Console. In the console, if I go to server configuration -> Client Access, go to the server properties -> Outlook Anywhere tab, the External host name field is populated correctly.

2 Answers 2


I had to set this up for a few clients a few years ago as well and didn't see this behavior. If it keeps resetting, it's possible that your registry isn't saving properly and/or it's being reset to default by a system service.

You could also set the permissions on the key to READONLY for everything but your administrative account to see if the behavior persists.

  • Hmm..., that's an interesting approach. Looking at the permissions I'm seeing that the key is only modifiable by domain admins, SYSTEM has only read permissions. None of the services run under any credentials in that group.
    – austinian
    Nov 12, 2014 at 17:07
  • Also, I'm not sure how the registry wouldn't be "saving properly" since immediately after I modify the data, outlook anywhere functionality returns to normalcy, so they're definitely in place.
    – austinian
    Nov 12, 2014 at 17:18

I finally found the answer via this article: http://blogs.technet.com/b/exchange/archive/2008/06/20/3405633.aspx

The PeriodicPollingMinutes key at


needs setting to zero to prevent RpcHttpConfigurator from updating the Valid Ports key automatically.

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