[Mimedefang] /etc/sysconfig/mimedefang option questions

[Rich West]

In the /etc/sysconfig/mimedefang file, there are the following options:

# If "yes", turn on the multiplexor relay checking function
# MX_RELAY_CHECK=yes
# If "yes", turn on the multiplexor sender checking function
# MX_SENDER_CHECK=yes
# If "yes", turn on the multiplexor recipient checking function
# MX_RECIPIENT_CHECK=yes

What *exactly* do each of these do?

I enabled them even though I am doing sender and recipient checks 
(rudimentary) within mimedefang-filter, but I'm curious to know if I 
just enabled something that was going to potentially block valid email.

Additionally, by enabling the MX_RELAY_CHECK, I've gotten a few syslog 
broadcasts:
Message from syslogd at myhost at Fri Oct 29 12:55:19 2004 ...
myhost perl: Host 211.228.227.141 claims to be my.numeric.ip.addr

I did set the syslog facility to "mail", and it does mention that I need 
to set "Also set $SyslogFacility in your filter", but where in the 
filter should that be set?

-Rich