Hello Friends,
I don't have static ip address. I had configured postfix and I am able to send mail to local users without any problem .
What when I try to send mail to my gmail id : it gives error
warning: relay host configuration problem
#postconf -n
alias_database = hash:/etc/aliases
alias_maps = hash:/etc/aliases
command_directory = /usr/sbin
config_directory = /etc/postfix
daemon_directory = /usr/libexec/postfix
debug_peer_level = 2
html_directory = no
inet_interfaces = all
mail_owner = postfix
mailq_path = /usr/bin/mailq.postfix
manpage_directory = /usr/share/man
mydestination = $mydomain, $myhostname, mail$mydomain
mydomain = linuxforfreshers.info
myhostname = phantom.phantom.linuxforfreshers.info
mynetworks = 172.24.0.0/16, 127.0.0.0/8
myorigin = $mydomain
newaliases_path = /usr/bin/newaliases.postfix
queue_directory = /var/spool/postfix
readme_directory = /usr/share/doc/postfix-2.3.3/README_FILES
relay_domains = $mydomain
relayhost = mail.$mydomain
sample_directory = /usr/share/doc/postfix-2.3.3/samples
sendmail_path = /usr/sbin/sendmail.postfix
setgid_group = postdrop
unknown_local_recipient_reject_code = 550

How can i send email to my gmail id.

Thanks in advance

This needs to be set to your ISP's outgoing mail server.