RPC over the HTTP(S) is the technical term for ‘Outlook Anywhere’ – the technology that allows you to access Exchange from an Outlook client via any Internet connection as if you were connected via the local network.

Outlook Anywhere is similar to the Server ActiveSync protocol used by Windows Mobile devices to access Exchange in that it is used to synchronise email, contacts and calendar with the client device, but whereas Server ActiveSync can only synchronise data with a specific user mailbox, Outlook Anywhere allows the user to use the full functionality of their Outlook client remotely – this includes accessing mailboxes other than their own (should they have permission to), public folders, everything they can do when connected locally in the office.

RPC stands for Remote Procedure Call. Whenever you perform an action in Outlook that requires a response from the Exchange server, Outlook sends a remote procedure call to the Exchange server and gets a response back.

What Outlook Anywhere does is to encrypt these remote procedure calls using a digital certificate and then send them to the Exchange server over the Internet, hence RPC over HTTPS.

Install RPC over HTTP Proxy Service

You first need to install the RPC over HTTP proxy service. This is a component of the Windows Server operating system and is installed via the Add/Remove Windows Components applet within the Control Panel. It is located under Networking Services (assuming you are running Server 2003 rather than Server 2008):

Enable Outlook Anywhere

The Outlook Anywhere function is enabled within the Exchange Management Console. Expand the Server Configuration container and select the Client Access folder:

Select the option to Enable Outlook Anywhere – a wizard will be displayed:

Enter the external name of the server and configure the authentication options to be used.

Install the SSL certificate on the client PC

Before you can use Outlook to connect to the Exchange server via RCP over HTTPS, you will first need to install the correct SSL certificate onto the client PC to authenticate the certificate used by the Exchange server. This is only necessary if you are using a self-issued certificate. If you are using a root-trusted certificate on the Exchange server then ignore this step.

The certificate that needs to be installed on the client PC is not the certificate used by the RPC virtual directory on the Exchange server, but the root certificate of the Certificate Authority that issued the certificate to the RPC directory.

To locate this certificate, log into the server that has the Certificate Authority service installed on it. This may well be the Exchange server itself, it depends on how your network is deployed.

On the server that is acting as the CA, open the Control Panel and open Internet Options.

Click on the Security tab and the on the Certificates button.

Click on the Trusted Root Certification Authorities tab.

Locate the certificate issued by the CA and export it as a CER file. Copy this file to the client PC.

On the client PC double click the CER file to install it. Select the option to install it to the Trusted Root Certification Authorities folder.

Configure the Outlook Client

NOTE – to use Outlook via RPC over HTTPS you will require Outlook 2003 or later.

Create a new Outlook profile if required.

Select the option to create an Exchange Server account.

In the Server Name field enter the LOCAL address of the Exchange server (ie the machine name, or the NETBIOS name)

Enter your username.

DO NOT CLICK NEXT at this point, click on the More Setting button.

You may receive an error saying that the Exchange server cannot be contacted, click OK. A further window will be displayed asking you to verify the address of the Exchange server, click Cancel.

The More Settings window will now be displayed. Click on the Connection tab:

Tick the option to Connect to Microsoft Exchange using HTTP. Click on the Exchange Proxy Settings button:

Enter the external web address of the Exchange server (ie the address used for Outlook Web Access) in the fields as shown above. In the second text field, the ‘msstd’ is required!

Click OK, OK again, Next and then Finish.

Now launch Microsoft Outlook.

You will be prompted to enter your NT domain login credentials:

Enter your username in the form ‘DOMAIN\Username’

You will now be connected to the Exchange server: