rc.sendmail

[John Von Essen]

Could someone please explain rc.sendmail to me? I am unclear why it 
does what it does. I currently have everything enabled in rc.conf:

     mta_start_script="/etc/rc.sendmail"
     sendmail_enable="YES"
(1) sendmail_flags="-L sm-mta -bd -q30m"
     sendmail_submit_enable="YES"
(2) sendmail_submit_flags="-L sm-mta -bd -q30m 
-ODaemonPortOptions=Addr=localhost"
     sendmail_outbound_enable="YES"
(3) sendmail_outbound_flags="-L sm-queue -q30m"
     sendmail_msp_queue_enable="YES"
(4) sendmail_msp_queue_flags="-L sm-msp-queue -Ac -q30m"

With the above settings, when I do a 'make start', only (1) and (4) get 
started. If I set sendmail_enable="NO", then only (2) and (4) start. If 
I set sendmail_enable="NO" and sendmail_submit="NO", then only (3) and 
(4).

This doesn't make any sense to me. For starters, why would I ever want 
just (3) and (4) running? Furthermore, I can't seem to get (1), (3), 
and (4) to all start together. I imagine people would want those three 
since you need your main sendmail running, and you could have a need 
for an "always-on" queue runner for mqueue and clientmqueue.

Thanks.
John