SMTP Configuration defines the settings for the SMTP protocol which is used by CMail Server to send email.
All email servers use the SMTP (Simple Mail Transport Protocol) to send Internet mail. To send mail from CMail Server to the Internet, you will need the hostname of your Internet Service Providers SMTP mail server. This information can be obtained your ISP's Technical Helpdesk.
CMail can use one of two methods for sending mail to the Internet. The first and easiest is to specify an upstream SMTP server, usually your Internet Service Provider's mail server. Once the ISP's mail server has taken delivery, it will handle the workload to get the message from A to B. The other method is to use MX resolution where CMail performs lookups to locate the position of the server on the Internet that handles the email for the person you are attempting to send the message to. Delivery by MX resolution can be slow as CMail attempts to communicate with the recipients email server directly but MX does provide ISP independence. See Advanced SMTP Configuration for MX Resolution Configuration.
Specifying an Upstream SMTP Mail Server
Other Options on the SMTP Configuration Menu
Kick SMTP Server
To counteract this problem, some mail servers will listen on a given port for kick requests and when one is received, will forward all of the mail its queue to the server making the kick request.
To enable this feature, check the Kick SMTP server on connection to the Internet checkbox. Note: This feature is not widely supported. Leave this option Unchecked unless you know for sure that your ISP supports Kick Server.