"pop3d start" reads the POP3 server configuration from /etc/courier/pop3d (and /etc/courier/pop3d-ssl) and runs couriertcpd(8) to accept new POP3 connections.
"pop3d-ssl start" reads /etc/courier/pop3d-ssl (and /etc/courier/pop3d) and runs couriertcpd(8) to accept new POP3-over-SSL connections.
| NOTE: | Thje Courier's POP3 server supports Maildir mailboxes only. |
"pop3d stop" "pop3d-ssl stop" shut down their respective servers.