In this video I have expained about How to Install and Configure Postfix to Send Mail Using Gmail and Google Apps on Ubuntu

Installation and Configuration Steps: hostnamectl set-hostname mail.krishnastechinfo.com

apt-get install libsasl2-modules postfix

nano /etc/postfix/sasl/sasl_passwd

[smtp.gmail.com]:587 username@gmail.com:password

postmap /etc/postfix/sasl/sasl_passwd

chown root:root /etc/postfix/sasl/sasl_passwd /etc/postfix/sasl/sasl_passwd.db chmod 0600 /etc/postfix/sasl/sasl_passwd /etc/postfix/sasl/sasl_passwd.db

nano /etc/postfix/main.cf

relayhost = [smtp.gmail.com]:587

Enable SASL authentication

smtp_sasl_auth_enable = yes

Disallow methods that allow anonymous authentication

smtp_sasl_security_options = noanonymous

Location of sasl_passwd

smtp_sasl_password_maps = hash:/etc/postfix/sasl/sasl_passwd

Enable STARTTLS encryption

smtp_tls_security_level = encrypt

Location of CA certificates

smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt

systemctl restart postfix

echo "Postfix" | mail -s "Postfix Testing" krishnastechinfo@gmail.com ... https://www.youtube.com/watch?v=duPHgexkk2I