Setting Up Email Notifications on Linux Servers Using sSMTP

Guides, Linux /

As a Linux server administrator, having a reliable email notification system in place is crucial. Whether you’re dealing with unattended upgrades, monitoring RAID arrays, or any other server-related alerts, getting quick notifications can make a world of difference. Here’s a quick guide to setting up sSMTP, a lightweight and straightforward alternative to postfix or other full-fledged mail transfer agents (MTAs).

Why sSMTP instead of postfix?

sSMTP is lightweight, easy to configure, and perfect for scenarios where you just need outgoing email functionality. It’s particularly well-suited for sending notifications from Linux servers without the overhead of a fully-fledged MTA like postfix.

How to install sSMTP

To get started, install sSMTP using your distribution’s package manager. On Ubuntu or Debian just type:

sudo apt update && sudo apt install ssmtp

For other distributions, the package name may vary slightly, but it’s typically ssmtp.

Configuring sSMTP

The primary configuration file for sSMTP is located at /etc/ssmtp/ssmtp.conf. Below is an example minimal configuration file you can use. Replace the placeholder values with your actual email credentials and server details:

# Config file for sSMTP sendmail

# The person who gets all mail for userids < 1000
# Make this empty to disable rewriting.
root=mail@example.com

# The place where the mail goes. The actual machine name is required; no
# MX records are consulted. Commonly mailhosts are named mail.domain.com
mailhub=mail.yourmailhost.com

# Where will the mail seem to come from?
rewriteDomain=yourmailhost.com

# The full hostname
hostname=serverhostname

# Are users allowed to set their own From: address?
# YES - Allow the user to specify their own From: address
# NO - Use the system generated From: address
FromLineOverride=YES

# Username/Password
AuthUser=noreply@example.com
AuthPass=securepassword
AuthMethod=LOGIN

Explanation of Key Parameters

  • root: Specifies who will receive system messages. Set this to your desired email address.
  • mailhub: Your SMTP server address (e.g., smtp.gmail.com).
  • rewriteDomain: The domain name to append to outgoing emails.
  • hostname: The server’s hostname.
  • FromLineOverride: When set to YES, users can define custom “From” addresses.
  • AuthUser/AuthPass: The credentials for your email account (e.g., a noreply account).

Testing the Configuration

Once configured, test your setup using the sendmail command, which sSMTP provides:

echo "Subject: Test Email" | sendmail -v your-email@example.com

This command sends a simple test email. The -v flag enables verbose output, helping you debug any issues.

Why Create a ‘noreply’ Address?

Using a noreply@example.com address is a best practice for automated emails. It ensures users know the email is for notifications only and not for correspondence.

Benefits of Having Email Notifications

  • Instant alerts for critical events.
  • Simplified server monitoring.
  • Enhanced troubleshooting through email logs.

By following these steps, you’ll have a lightweight, effective email notification system in place for your Linux servers.