Sendmail : Configure outgoing relay server

Edit following in /etc/mail/sendmail.cf and add the name of your outgoing/relaying mailhost. Ensure that the relay server is accepting your email first.

# "Smart" relay host (may be null)
DS

e.g. if the outgoing relay is mailhost.xyzserver.com sendmail configuration should look like following.

# "Smart" relay host (may be null)
DS mailhost.xyzserver.com

After that restart the sendmail.

/etc/init.d/sendmail stop
/etc/init.d/sendmail start