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How to Enable RPC over HTTP Connectivity

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This article refers to Microsoft Exchange Server 2007, 2010, 2013, 2016, and 2019.

RPC over HTTP (RoH), also known as Outlook Anywhere, is required by Exchange Server 2013 and newer. This connection may also be required with earlier versions of Exchange Server if the Barracuda Cloud Archiving Service cannot reach the Exchange Server directly, for example, if they are installed in different locations.

RoH must bind to your email service account; for details on setting up an email service account, refer to Creating an Email Service Account for Exchange Server 2007, 2010, 2013, 2016, and 2019.


Self-signed certificates are currently not supported. You must be using a trusted CA root certificate in order to utilize the Exchange Integration feature.


If you are already using NTLM authentication in your environment, you may want to set your RPC virtual directory to use both Basic and NTLM authentication to avoid Outlook users being prompted for login information at each Outlook session. For additional information, see the Microsoft TechNet article RPC over HTTP Authentication and Security.

Enable RoH Capability

Use the following steps to enable RoH capability for Exchange integration:

  1. Log into the Barracuda Cloud Archiving Service web interface.
  2. On the Mail Sources > Exchange Integration page, click Start New Action.
  3. Select an action, and click Add New Server.

  4. Enter the Exchange Server details.

    Exchange Server Details

    Enter either your mailbox server hostname or your Exchange RPC Endpoint. For Exchange Server 2013, you can also use the mailbox ID@domain format, for example:

    Important: This format is required for hosted Exchange 2013 providers.

    For more information, refer to the Microsoft TechNet article What's New in Exchange 2013.

  5. Once you have entered the Exchange Server details, click Advanced Options.

  6. Enter the proxy server that is to provide RoH connectivity; that is, enter the Hostname of the RoH Proxy itself in the Advanced > Proxy field. RoH will be used if available.

    Hosted Providers

    If you are connecting to a hosted Exchange provider, the configuration provided by your vendor may not include all details necessary for the Barracuda Cloud Archiving Service. To determine the correct mailbox and RoH proxy servers, you can confirm your details using Microsoft's Exchange Connectivity Test site. For more information, refer to the Troubleshooting section below.

    Exchange Configuration Testing

    For information on testing your Exchange configuration using tools available from Microsoft, refer to the Troubleshooting section below. These tools will help confirm that details such as the required SSL certificates, Basic Authentication mode, and correct server name/ Exchange instance name and RoH proxy are being used.

    Verify that both HTTP basic authentication and SSL (HTTPS) are enabled on the RoH proxy server; both are enabled by default. The RoH proxy server must be using a trusted, third-party certificate. If you have questions, contact Barracuda Networks Technical Support.

  7. Click Save, and follow the onscreen directions to set up the action.

Note that if you have a scheduled action in the table you can also enable RoH using the following steps:

  1. Click Edit in the Scheduled Actions table, and go to the Select Server page.
  2. Click Edit following the server name, and click Advanced Options in the Edit Server page.
  3. Enter the Proxy Server, Click Save, click Continue twice, and then click Submit.

Confirm RoH is Available

Use the following steps to confirm RoH is available to the Barracuda Cloud Archiving Service by testing through your web browser:

  1. Enter the Exchange CAS Server in a browser window in the form https://<CAS>/rpc, for example, https://RoH server address/rpc

    https://RoH server address/rpc/RpcProxy.dll may be necessary.

  2. Your browser should indicate that the RoH proxy's SSL certificate is trusted.
  3. You should be challenged for your credentials by the browser; enter the Barracuda Cloud Archiving Service account credentials.

  4. Your credentials should be accepted, and you should see a blank page, be redirected to a different site, or receive an HTTP 503 error. This is expected. You should not encounter any other HTTP errors.


Use this section to test your Exchange configuration.

Test Remote Connectivity

Use Microsoft's Remote Connectivity Analyzer to test connectivity set up criteria, for example:

  • Test whether Exchange Server is providing RoH
  • Verify basic authentication is enabled; basic authentication is required
  • Verify proper certificate chain is loaded

For example, from the Exchange Server tab you can test your Exchange Server RoH configuration, and from the Client tab you can download a standalone test client to your local workstation.

The remote connectivity tool is available from the Microsoft website:

Test RoH Connectivity Using Outlook

Use the following steps to verify your RoH configuration:

  1. Go to the Mail applet in the Outlook Control Panel; the exact appearance of the Mail applet varies depending on your version of Windows and Outlook:
  2. Click Show Profiles:
  3. Click Add to create a temporary profile. Enter the Profile Name:
  4. Click OK. In the Add Account page, select Manual setup or additional server types:

    Do not attempt to automatically configure this profile.

  5. Click Next. Select Microsoft Exchange Server or compatible service:
  6. Click Next. Enter the Exchange Server hostname in the Server field, and enter the Barracuda Cloud Archiving Service account name in the User Name field:
  7. Click More Settings. In the Microsoft Exchange dialog box, click the Connection tab, and turn on Connect to Microsoft Exchange using HTTP:

    Depending on the version of Outlook you are running, warning messages may display alerting you to Exchange Server connection issues; this is expected as RoH is not yet configured. You can ignore these error messages at this step in the process.


  8. Click Exchange Proxy Settings. In the Microsoft Exchange Proxy Settings dialog box, complete the following:
    • Enter the RoH proxy server hostname in the https:// field.
    • Turn on Connect using SSL only.
    • Select Basic Authentication from the Proxy authentication settings drop-down menu.
  9. Click OK to save your RoH configuration, and then click OK to close the Microsoft Exchange dialog box.
  10. In the Add Account dialog box, click Check Name. You should be challenged for your credentials. Enter the Barracuda Cloud Archiving Service account credentials. You should be able to authenticate, and the username that you entered in the Add Account dialog should resolve successfully.
  11. Click Cancel in the dialog box to remove the temporary Outlook profile. If a message displays asking if you want to create a profile without any email account, click Cancel.