To set up ETRN, you need to configure the server and the client separately. The ISP usually configures the server side. The setup is simple if your ISP is using Exchange Server. Go to the Connections tab of the IMS property sheet. Under Message delivery, click E-Mail Domain. Add the customer's domain name and select the Queue messages for ETRN check box, as you see inScreen 1. If you don't check this box, the ISP server will immediately attempt to deliver messages even though the ETRN client is offline. Checking this box prevents unsuccessful retries and nondelivery reports (NDRs) back to the originator. ISPs that don't use Exchange Servers can configure the Sendmail utility for ETRN capability.
The ETRN client requires more complex configuration. First, configure when the ETRN client sends mail. If you're using RAS, be sure you've configured the RAS client and a phone book entry pointing to your ISP before you begin. From Exchange Server, go to the IMS property sheet to configure your connector for ETRN dial-up. From the Dial-up Connections tab, which Screen 2 shows, choose the appropriate remote access entry from the Available connections window.
Next, decide on a schedule for calling your ISP. As Screen 2 shows, you have several options, including transferring mail at specific intervals or whenever mail is queued up. Note that you don't explicitly define when to close the connection. The IMS terminates the connection depending on the setting in the Time-out after X min window. This parameter refers to idle time; the connection closes after the number of minutes you specify have passed. Your ISP must be able to dequeue your inbound mail within this period, or the connection will close prematurely. The connection might close if the dequeue process doesn't proceed in a timely fashion after you've established the connection with the ISP. You can accommodate a slow start of the dequeuing process by increasing the time