rc.conf: document the sendmail options

While here remove the deprecation of the sendmail_enable="NONE" as
it has been deprecated for 20 years and never removed

share/man/man5/rc.conf.5

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd November 9, 2022
+.Dd November 10, 2022
 .Dt RC.CONF 5
 .Os
 .Sh NAME
@@ -4709,6 +4709,162 @@ which means that the script will attempt to unlock all datasets.
 Define the total number of seconds to wait for the zfskeys script
 to unlock an encrypted dataset.
 The default is 10.
+.It Va sendmail_enable
+.Pq Vt str
+If set to
+.Dq Li YES ,
+run the
+.Xr sendmail 8
+daemon at system boot time.
+If set to
+.Dq Li NO ,
+do not run a
+.Xr sendmail 8
+daemon to listen for incoming network mail.
+This does not preclude a
+.Xr sendmail 8
+daemon listening on the SMTP port of the loopback interface.
+The
+.Dq Li NONE
+option sets each
+.Va sendmail_enable ,
+.Va sendmail_submit_enable ,
+.Va sendmail_outbound_enable ,
+.Va sendmail_msp_queue_enable
+to
+.Dq Li NO .
+.It Va sendmail_cert_create
+.Pq Vt str
+If
+.Va sendmail_enable
+is set to
+.Dq Li YES ,
+create a signed certificate
+.Pa /etc/mail/certs/host.cert
+representing
+.Pa /etc/mail/certs/host.key
+by the CA certificate in
+.Pa /etc/mail/certs/cacert.pem .
+This will enable connecting hosts to negotiate STARTTLS allowing incoming
+email to be encrypted in transit.
+.Xr sendmail 8
+needs to be configured to use these generated files.
+The default configuration in
+.Pa /etc/mail/freebsd.mc
+has the required options in it.
+.It Va sendmail_cert_cn
+.Pq Vt str
+If
+.Va sendmail_enable
+is set to
+.Dq Li YES
+and
+.Va sendmail_cert_create
+is set to
+.Dq Li YES ,
+this is the Common Name (CN) of the certificate that will be created.
+If
+.Va sendmail_cert_cn
+is not set, the system's hostname will be used.
+If there is no hostname set,
+.Dq Li amnesiac
+will be used.
+.It Va sendmail_flags
+.Pq Vt str
+If
+.Va sendmail_enable
+is set to
+.Dq Li YES ,
+these are the flags to pass to the
+.Xr sendmail 8
+daemon.
+.It Va sendmail_submit_enable
+.Pq Vt bool
+If set to
+.Dq Li YES
+and
+.Va sendmail_enable
+is set to
+.Dq Li NO ,
+run
+.Xr sendmail 8
+using
+.Va sendmail_submit_flags
+instead of
+.Va sendmail_flags .
+This is intended to allow local mail submission via
+a localhost-only listening SMTP service required for running
+.Xr sendmail 8
+as a non-set-user-ID binary.
+Note that this does not work inside
+.Xr jail 2
+systems, as jails do not allow binding to just the localhost interface.
+.It Va sendmail_submit_flags
+.Pq Vt str
+If
+.Va sendmail_enable
+is set to
+.Dq Li NO
+and
+.Va sendmail_submit_enable
+is set to
+.Dq Li YES ,
+these are the flags to pass to the
+.Xr sendmail 8
+daemon.
+.It Va sendmail_outbound_enable
+.Pq Vt bool
+If set to
+.Dq Li YES
+and both
+.Va sendmail_enable
+and
+.Va sendmail_submit_enable
+are set to
+.Dq Li NO ,
+run
+.Xr sendmail 8
+using
+.Va sendmail_outbound_flags
+instead of
+.Va sendmail_flags .
+This is intended to allow local mail queue management
+for systems that do not offer a listening SMTP service.
+.It Va sendmail_outbound_flags
+.Pq Vt str
+If both
+.Va sendmail_enable
+and
+.Va sendmail_submit_enable
+are set to
+.Dq Li NO
+and
+.Va sendmail_outbound_enable
+is set to
+.Dq Li YES ,
+these are the flags to pass to the
+.Xr sendmail 8
+daemon.
+.It Va sendmail_msp_queue_enable
+.Pq Vt bool
+If set to
+.Dq Li YES ,
+start a client (MSP) queue runner
+.Xr sendmail 8
+daemon at system boot time.
+As of sendmail 8.12, a separate queue is used for command line
+submissions.
+The client queue runner ensures that nothing is
+left behind in the submission queue.
+.It Va sendmail_msp_queue_flags
+.Pq Vt str
+If
+.Va sendmail_msp_queue_enable
+is set to
+daemon.
+.Dq Li YES ,
+these are the flags to pass to the
+.Xr sendmail 8
 .El
 .Sh FILES
 .Bl -tag -width "/etc/defaults/rc.conf" -compact
@@ -4808,6 +4964,7 @@ The default is 10.
 .Xr rwhod 8 ,
 .Xr savecore 8 ,
 .Xr sdpd 8 ,
+.Xr sendmail 8 ,
 .Xr service 8 ,
 .Xr sshd 8 ,
 .Xr swapon 8 ,