Nagios could not send notification through email

Basically, OSCC had customize Nagios using Postfix for sending email. Unfortunately the email could not go through. After all the Googling the solution is quite simple.

Just edit file name
/etc/postfix/main.cf


add a new line with
relayhost = mpkmail.rmp.gov.my


Below are template provide by OSCC;

####################################################################

# See /usr/share/postfix/main.cf.dist for a commented, 
# more complete version


# Debian specific:  Specifying a file name will cause the first
# line of that file to be used as the name.  The Debian default
# is /etc/mailname.
# myorigin = /etc/mailname

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no

# appending .domain is the MUA's job.
append_dot_mydomain = no

# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h

readme_directory = no

# TLS parameters
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_use_tls = yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc
# paackage for information on enabling SSL in the smtp client.

myhostname = mydesktopmanager.oscc.org.my
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = oscc.org.my, mydesktopmanager.oscc.org.my, localhost.oscc.org.my, localhost
relayhost = mpkmail.rmp.gov.my
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all

#################################################################### 

Don't forget to visit this URL for more detail http://nagios.sourceforge.net/docs/3_0/configmain.html