Configure Postfix to sent emails using MailGun

First install requirements

apt-get update && apt-get install postfix libsasl2-modules -y

Run

sed -i "s/default_transport = error/# default_transport = error/g" /etc/postfix/main.cf
sed -i "s/relay_transport = error/# relay_transport = error/g" /etc/postfix/main.cf
sed -i "s/relayhost =/# relayhost =/g" /etc/postfix/main.cf

Edit /etc/postfix/main.cf

vi /etc/postfix/main.cf

Add

relayhost = [smtp.mailgun.org]:2525
smtp_tls_security_level = encrypt
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous

Create file /etc/postfix/sasl_passwd

echo "[smtp.mailgun.org]:2525 SMTP_LOGIN:SMTP_PASSWORD" > /etc/postfix/sasl_passwd

Replace SMTP_LOGIN and SMTP_PASSWORD with your user and password you get from mailgun.

Run

postmap /etc/postfix/sasl_passwd

Restart postfix

service postfix restart

You can test email with

echo "test" | mail -s "test" [email protected]