Dial-up systems are not connected to the Internet all the time. As a result, most of the time other systems cannot send mail directly to your dial-up server.
You can use three methods to receive incoming E-mail messages:
- store all mail in a Unified Domain-Wide Account on your ISP server, and retrieve it from there periodically, using the RPOP module.
- specify your ISP mail server as your mail backup server, and use the SMTP Remote Queue Starting (ETRN) feature to retrieve mail using the SMTP module.
- specify your ISP mail server as your mail server (main MX), and use the SMTP ATRN feature to retrieve mail using the SMTP module. The ISP mail server should be able to handle the ATRN requests. If the ISP server is a CommuniGate Pro Server, too, it should be configured to hold mail for your Domain and to accept ATRN commands from your Server.
Your Server should have a static IP address to be able to receive mail via SMTP (using ETRN). If your ISP assigns you an IP address dynamically, and each time your Server can get a different IP address, retrieving mail using the SMTP ATRN module or the RPOP module are the only choices.