Any AppRiver Hosted Exchange customer that needs to deliver email to both AppRiver Hosted Exchange and an alternate e-mail server.


  •  The alternate server must be able to receive traffic over the following IP:  EXG7:

  •  An active Exchange account set up properly in the Customer Portal (



Part I - Basic Overview of Split-Domain Routing (SDR)

1. Split-Domain-Routing is a feature that splits your domain among two different mail servers, while existing on both at the same time. The e-mail comes to AppRiver via MX records from the Internet and is routed to the Hosted Exchange server to see if the recipient exists there. If the recipient does exist, the e-mail is delivered. If not, the e-mail is then routed out the SDR to the alternate mail server’s address and the e-mail is delivered there. 

 2. This process is typically used during the trial period, where one user is added to Hosted Exchange to test the system while leaving the rest of the users on their current system. Once the customer accepts the trial, their users may be migrated to AppRiver a few at a time rather than having to move everyone at once.  

3. Another SDR option is a HEX/POP combo; e.g., the CEO and his assistant (and possibly others) are added to Hosted Exchange for administration purposes (shared contacts/calendaring) and the rest of the users are given a simple POP3 e-mail account. Please be aware that there is an extra charge for this service. (Please contact our sales team for more information.) 

4. Please note that if you use SDR, your domain name will exist on two separate servers. Once your trial account has been converted to active, you must point your SDR to your server. Our server will no longer be available. 

Example: exists on your server and our server. This presents an issue when someone on your server wants to e-mail someone on our system because your server will not see the Exchange user. Basically, if the user does not exist on your system, your server yields a “Recipient not found” error.   

5. To solve this problem, simply create a forwarder on your server to facilitate e-mail transport in the form of See the below example for clarification.

6. In the above situation, the user, John, needs to e-mail the user, Bill. John creates an e-mail to and sends it. Once he does this, he received an undeliverable message saying that the recipient cannot be found. This is due to the fact that Bill is not on that same server, so the server correctly reports that Bill does not exist at To solve this problem, create a forwarder on the alternate (In-house) server in the form, where .com may be .net, .org, etc. Note that the # refers to the Exchange island you are set up on (7).

7. When John sends an email to Bill this time, there is now an actual account and the e-mail is then forwarded over to Exchange into Bill's actual mailbox via the forwarding address. Note that a forwarder must be set up on the the alternate server for every account that is on AppRiver’s Hosted Exchange.

Part II - SDR Setup in AppRiver's Hosted Exchange Environment 

1. To set up Split-Domain Routing for your domain, log into the Customer Portal (with an admin account) at Once you are in, click the Exchange tab and then Routing.

2. Once you select the Enable domain routing check box, the Routing section will expand. Enter your Server IP address or Hostname in the Alternate e-mail server text box, the Port that it receives e-mail, (typically 25), and the number of users utilizing your server. Click the Save button to complete the split route.

3. Please note that if you are routing to your own server, you must ensure that you allow connections from our servers on the following IP, which is noted on the SDR page.

    EXG7 (Exchange) island:

4. Once SDR has been set in the Customer Portal, perform a test using the Test Settings section. Enter an e-mail address in the From field and a valid e-mail address that is resident on the alternate server in the Test Recipient field. Click Test. You will see a response as to whether the test was successful or not. 

5. While this is a handy tool, it can still, under certain circumstances, give erroneous results. The best way to test a SDR is to send a test message from an account on the hosted Exchange server, via OWA, to an account on the alternate mail server.   

Related Links:

How enable split-domain routing when migrating from Exchange to Hosted Exchange (