Sendmail anti-relay

I have setup sendmail in RH 8, all send and receive email is ok, but I have one questino about anti-relay which is.
Let's say, my RH 8 sendmail sever IP is 192.168.1.1 and other PC IP is 192.168.1.2 which are all in the LAN.
Let's see my setup step first
(1) vi /sendmail.cf --
 O DaemonPortOptions=Port=smtp,Addr=192.168.1.1, Name=MTA
(2) assume I have abc.com this domain, then I vi /etc/mail/local-host-names
(3)add email account by useradd................

With the above setting, I can send and receive email, but
I don't know why I no need to edit /etc/mail/access since
default is don't relay any things except these  
localhost.localdomain           RELAY
localhost                       RELAY
127.0.0.1                       RELAY

I haven't add 192.168.1.1   RELAY
why sendmail server still accept the mail from 192.168.1.1 ?

Thanks you very much !