If you want to send an email using a smart host, I hope you understand that even the Smart Host should be running some SMTP server software like Sendmail or Postfix to relay it on internet. Even if your sendmail is relaying the mail to smart host properly and smart host is not configured properly to relay mails from outside or is not installed with some smtp server software, you will never receive any emails. I hope you have rebuild sendmail.cf using m4 macro and the correct sendmail.mc. If that is not working just add
to sendmail.cf.
You should have logs probably in /var/log/maillog file.

Hi all,

Thnx for your support.
It has been resolve with your support. i was making very silly mistake. i was entering ip address but i forgot to include it in reverse lookup zone in dns server. that's why it was not able to resolve the host name. when i entered FQDN. it's done thnx for your support guys..

but one more support i want from you that i made the changes into sendmail.mc and ran "#m4 sendmail.mc > /etc/mail/sendmail.cf"
then i restarted sendmail service but it still i could not see my mail relay in sendmail.cf then i manually edited sendmail.cf and restarted the service. then it started working fine..

am i making mistake while rebuilding sendmail.cf through sendmail.mc? if not then why i am not getting mail relay in sendmail.cf in DS.

well, # is a comment initialiser

so if you litrally did #m4 ...
it did nothing.

No i did not do like this . i did like
m4 sendmail.mc > /etc/mail/sendmail.cf