Ports - Internet Ports - Mail tab

From this tab you can enable and configure TCP/IP and SSL ports for the SMTP, IMAP, and POP3 Internet mail protocols.

On servers that use Internet Site documents, Internet mail services obtain port authentication settings from the Security tab of an Internet Site document, rather than from the Server document. As a result, when Internet Site documents are used, TCP/IP and SSL port authentication settings are not available in the Server document. Settings in the Server document still provide the port numbers and status for the TCP/IP and SSL ports, and enable each of the Internet mail services to honor server access restrictions.

If the server uses Internet Site documents, then you must use Site documents to configure all Internet mail service protocols on the server. If a Site document for a particular Internet mail service is not present in the Domino® Directory, or the authentication options in the Site document for that service are set to No, users cannot connect to the service. Clients attempting to connect to the service receive the following error:

This site is not enabled on the server.