Email Sending Using Postfix Service on Linux Machine

Introduction:

This blog post is a second part continuation of an earlier post regarding shell script that checks CPU Utilization for a given period of time. In this article, I will share to you a comprehensive step by step procedure on how to send an email message via linux machine, using postfix service. After configuring this, we will have a new article that will show how to integrate threshold breaching shell script and alert notification via email message, combining all three articles to come up with a very robust email notification alerting upon CPU Utilization Breach via shell script.

Installation and Configuration of Postfix

Postfix is a widely-used open-source mail transfer agent (MTA) in Unix-like operating systems. It serves as the backbone for routing and delivering email across networks, handling tasks such as receiving, processing, and forwarding messages. Known for its security, reliability, and extensibility, Postfix offers a robust solution for managing email services in both small-scale setups and large enterprises.

1. Install Postfix in your linux machine

yum install -y postfix

2. Start the Postfix service and check its status

systemctl start postfix
systemctl status postfix

3. Configuring Postfix

vi /etc/postfix/main.cf
#Config
mydomain = localhost
relayhost = [smtp.gmail.com]:587
smtp_sasl_auth_enable = yes
smtp_sasl_security_options = noanonymous
smtp_tls_security_level = encrypt
smtp_tls_CAfile = /etc/pki/tls/certs/ca-bundle.crt
inet_interfaces = all
#Ensure that the other “inet_protocols = all”, “smtp_tls_security_level = encrypt” and “inet_interfaces = localhost” in the configuration file are commented already.

4. Creating sasl_password file

vi /etc/postfix/sasl_passwd
[smtp.gmail.com]:587 <email addr sender>:<gmail app password>

5. Restart Postfix, Postmap Command and chmod Command

systemctl restart postfix
postmap /etc/postfix/sasl_passwd
chmod 600 /etc/postfix/sasl_passwd /etc/postfix/sasl_passwd.db

6. Send Email Test

echo “Hi Engineer! today is $(date)” > File2
/usr/sbin/sendmail [email protected] < File2

Conclusion

In this article we have seen a very insightful step by step procedure on how to install, configure and use postfix service to send email message via linux machine, in later articles, we’ll integrate the learnings from the CPU Utilization Monitoring Script and then configure a CPU Util Breaching Script with Alert Notification via Email all in one Script.