I am on redhat 7.2 i am feeling some error that my problem is that

i am using my isp i configure there in send taht

DSmail.mywebsite.com

and

the second configuration is

O DaemonPortOptions=Port=smtp,Addr=192.168.1.1, Name=MTA

that is my server ip

and on client i am using windows 98

tell me when i am sending mail from isp mail through on my yahoo account then error occurs

myusername sendmail[3588]: g3LGYcu03586: g3LGYsu03588: DSN: User unknown
Apr 21 21:37:40 myusername sendmail[3642]: g3LGbCn03642: to=<myusername@yahoo.com>, delay=00:00:28, xdelay=00:00:28, mailer=relay, pri=31248, relay=mail.mywebsite.com [202.63.192.11], dsn=2.0.0, stat=Sent (Message queued)

and my access file in /etc/mail/access directory is like

localhost RELAY
127.0.0.1 RELAY
192.168.1.1 RELAY
192.168.1.2 RELAY
#myusername.champ.com RELAY
202.63.192 RELAY

plz solve my problem