/etc/postfix/main.cf

myorigin = /etc/mailname

smtpd_banner = $myhostname ESMTP

delay_warning_time = 4h

myhostname = your_host_name
mydomain = your_host_name

mydestination = localhost

mynetworks = 127.0.0.0/8

inet_interfaces = your_ip_address 127.0.0.1

smtp_bind_address = your_ip_address
mynetworks_style = host

/etc/mailname

your_mail_name