Many of the tasks to perform before configuring the mail service are out of your control, making it frustrating. Now for the easy part. To set up the mail service is one of the easier tasks to perform in Lion Server. One reason being that Lion Server comes with a Service Configuration Assistant that will configure the server as needed. First, enable the Mail service.
To enable the mail service, open Server Admin and click on the name of the server in the Server Admin sidebar. Then click on Settings in the Server Admin toolbar (horizontally at the top of the Server Admin window) and click on the Services tab. Click on the checkbox for the Mail service and then click on Save.
The Mail service will appear under the name of the server. Click on the service and then click on the Overview button in the Server Admin toolbar. Click on the Configure Mail Service… button to bring up the Service Configuration Assistant for the mail service, which will guide you through the setup of a mail server.
At the Introduction screen, a list of technologies that comprise the Mail service is shown (e.g., Postfix, Dovecot, Kerberos, Mailman, etc.). Click on Continue to proceed to the Mail Service: General screen. Here, use the first three checkboxes to enable each protocol used in your environment. These include the following:
Downloads messages to your computer, usually removing them from the server immediately or after a certain number ...