sendmail can't send mail from local mail server?

[shams]

hi,
i have doamin example.other.sc from dyndns.com, runing a webserver in fc5, i can browse my webserver without problem,now i am trying to setup a local mail server using sendmail, i can recieve mails but can't send, because sendmail cannot attach my domain with my user name like user@example.other.sc but sending as user@localhost.localdomain, these are the changes i made to /etc/mail files:
in sendmail.mc:
LOCAL_DOMAIN(`example.other.sc')dnl
FEATURE(`relay_based_on_MX')dnl
MASQUERADE_AS(`example.other.sc')dnl
FEATURE(masquerade_envelope)dnl
FEATURE(masquerade_entire_domain)dnl
MASQUERADE_DOMAIN(localhost)dnl
MASQUERADE_DOMAIN(localhost.localdomain)dnl
MASQUERADE_DOMAIN(example.other.sc)dnl

in access file:
# by default we allow relaying from localhost...
localhost.localdomain RELAY
localhost RELAY
127.0.0.1 RELAY
example.other.sc RELAY

in local-host-names file:
# local-host-names - include all aliases for your machine here.
example.other.sc

in relay-domains file:
example.other.sc

in virtusertable file:
@example.other.sc user

after make this is the output when i restart the sendmail:
# /etc/rc.d/init.d/sendmail restart
Shutting down sendmail: [ OK ]
Shutting down sm-client: [ OK ]
Starting sendmail: [ OK ]
Starting sm-client: [ OK ]

and this is my /etc/hosts file:
127.0.0.1 localhost.localdomain.com localhost
202.153.68.123 example.other.sc

any one can help please?