First of all you will need certain packages:
apt-get install postfix ssl-cert mailutils libsasl2-modules
Then you need to create /etc/postfix/main.cf
daemon_directory = /usr/lib/postfix myorigin = yourdomain.com mydomain = yourdomain.com myhostname = yourdomain.com smtp_generic_maps = hash:/etc/postfix/generic header_checks = regexp:/etc/postfix/header_checks relayhost = [smtp.gmail.com]:587 smtp_sasl_auth_enable = yes smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd_gmail smtp_sasl_security_options = noanonymous smtp_tls_CAfile = /etc/postfix/cacert.pem smtp_use_tls = yes smtp_tls_security_level = encrypt smtp_enforce_tls = yes disable_dns_lookups = yes message_size_limit = 35651584 smtp_destination_rate_delay = 60 relay_destination_rate_delay = 60 inet_protocols = ipv4 mynetworks = 127.0.0.1 alias_maps = hash:/etc/aliases
Then edit /etc/postfix/sasl_passwd_gmail
[smtp.gmail.com]:587 yourname@yourmail.com:YOURPASSWORD
Then edit /etc/postfix/header_checks
/^To:.*@hostname.localnet/ REDIRECT yourname@yourdomain.com /^From:(.*@yourdomain.com[>]*)/ PREPEND Reply-To:$1
Then edit /etc/postfix/generic
root@yourdomain.com yourname@yourdomain.com root@hostname.localnet yourname@yourdomain.com sudoer@hostname.localnet yourname@yourdomain.com
Then execute following commands:
postmap /etc/postfix/generic postmap /etc/postfix/sasl_passwd_gmail cat /etc/ssl/certs/Equifax_Secure_CA.pem >/etc/postfix/cacert.pem ln -s /etc/postfix/aliases.db /etc/aliases.db #remove /etc/aliases.db if exists postalias /etc/postfix/generic postalias /etc/aliases /etc/init.d/postfix restart
And finally send your test email:
echo "body of your test email message" | mail -r "yourname@yourdomain.com" -s "Subject of your email message" someother@emailaddress.com