Some more info Courier is enabled in the services in yast.
System Services (Runlevel): Services
│apache2 │Yes │Apache2 httpd │
│atd │No │Start AT batch job daemon │
│autofs │No │Start the autofs daemon for automatic mounting of file│
│autoyast │No* │A start script to execute autoyast scripts │
│bastille-firewall │No* │ │
│bluetooth │No │Bluetooth protocol stack services ┴
│courier-authdaemon │Yes │Courier-IMAP Authentication server │
│courier-imap │Yes │Courier-IMAP server │
│courier-imap-ssl │Yes │Courier-IMAP server for SSL connections │
│courier-pop │Yes │Courier-POP3 server │
│courier-pop-ssl │Yes │Courier-POP3 server for SSL connections
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