man courieresmtpd (Administration système) - Courier mail server ESMTP daemon
NAME
courieresmtpd - Courier mail server ESMTP daemon
DESCRIPTION
The actual Courier ESMTP daemon (mail transfer agent) is called courieresmtpd. Normally, courieresmtpd is run from couriertcpd, which is in turn run from esmtpd start or a similar command. You should not have to run courieresmtpd manually.
SEE ALSO
couriertcpd(8), esmtpd(8).