UBUNTU - SENDMAIL SETUP (SMART_HOST)

Thanks to sifoo & reference site:  http://www.cyberciti.biz/faq/configure-sendmail-as-a-smart-host/ 

The SMART_HOST macro allows you to specify the host that should relay all outgoing mail that you are unable to deliver directly, and the mail transport protocol to use to talk to it.

Make sure sendmail was install in your server, if not install first:
  # aptget install sendmail                                                                    

Open your configuration file:# vi /etc/mail/sendmail.mcAppend or modify macro that read as follows :define(`SMART_HOST',`smtp.net4india.com')Replace smtp.net4india.com with your actual smtp server address. If line contains word, dnl remove the dnl word. Regenerate a new sendmail.cf config file with m4 command:# m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cfRestart sendmail service:# /etc/init.d/sendmail restart

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