How To Install Sendmail on Ubuntu 22.04 LTS

In this tutorial, we will show you how to install Sendmail on Ubuntu 22.04 LTS. For those of you who didn’t know, Sendmail is an open-source Mail Transfer Agent (MTA) which is used to route emails using a server or by using shell commands. It includes SMTP (Simple Mail Transfer Protocol) for mail transfer and email delivery. Most of the system administrators preferred to use the Sendmail server as MTA over other MTAs. You can also use the Sendmail server to send emails via external SMTP servers like Gmail, Amazon SES, MailChimp, etc.

This article assumes you have at least basic knowledge of Linux, know how to use the shell, and most importantly, you host your site on your own VPS. The installation is quite simple and assumes you are running in the root account, if not you may need to add ‘sudo‘ to the commands to get root privileges. I will show you the step-by-step installation of Sendmail on Ubuntu 22.04 (Jammy Jellyfish). You can follow the same instructions for Ubuntu 22.04 and any other Debian-based distribution like Linux Mint, Elementary OS, Pop!_OS, and more as well.

Prerequisites

• A server running one of the following operating systems: Ubuntu 22.04, 20.04, and any other Debian-based distribution like Linux Mint.
• It’s recommended that you use a fresh OS install to prevent any potential issues.
• SSH access to the server (or just open Terminal if you’re on a desktop).
• A non-root sudo user or access to the root user. We recommend acting as a non-root sudo user, however, as you can harm your system if you’re not careful when acting as the root.

Install Sendmail on Ubuntu 22.04 LTS Jammy Jellyfish

Step 1. First, make sure that all your system packages are up-to-date by running the following apt commands in the terminal.

sudo apt update
sudo apt upgrade
sudo apt install wget apt-transport-https gnupg2 software-properties-common

Step 2. Installing Sendmail on Ubuntu 22.04.

By default, Sendmail is available on Ubuntu 22.04 base repository. Now run the following command below to install the latest version of Sendmail to your Ubuntu system:

sudo apt install sendmail

Step 3. Configure Hostname.

Find your hostname using the following command:

hostname

Next, open the file using your favorite text editor:

nano /etc/hosts

On the line starting with 127.0.0.1, add the hostname to the end as it looks below. This should be on a single line:

127.0.0.1 localhost your-hostname

Step 4. Configure SMTP.

Now we create a new directory inside /etc/mail directory for SMTP configuration:

sudo mkdir /etc/mail/authinfo

Set the correct permission for the file:

sudo chmod -R 700 /etc/mail/authinfo

Then, create a new file for your SMTP authentication inside the newly created directory:

cd /etc/mail/authinfo
nano smtp-auth

Add the following line and replace the email address with your login email and password with your password:

AuthInfo: "U:root" "I:your-email-address" "P:your-strong-password"

Save and exit the file then, create a hash database map for the above-created authentication:

sudo makemap hash smtp-auth < smtp-auth

Step 5. Configure SMTP.

Now we switch to the Sendmail configuration directory and edit the sendmail.mc file:

cd /etc/mail
nano sendmail.mc

Add the below configurations right after the MAILER _DEFINITIONS line and also replace smtp-host with your SMTP hostname:

define(`SMART_HOST',`[smtp-host]')dnl
define(`RELAY_MAILER_ARGS', `TCP $h 587')dnl
define(`ESMTP_MAILER_ARGS', `TCP $h 587')dnl
define(`confAUTH_OPTIONS', `A p')dnl
TRUST_AUTH_MECH(`EXTERNAL DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl
define(`confAUTH_MECHANISMS', `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl
FEATURE(`authinfo',`hash -o /etc/mail/authinfo/smtp-auth.db')dnl

Step 6. Rebuild Sendmail Configuration.

Now rebuild the Sendmail configuration using the following command below:

cd /etc/mail
sudo make

Once is done, now we restart the Sendmail service:

sudo systemctl restart sendmail

Step 7. Simple PHP Script for Sending Emails.

Now we create a PHP file send-email.php in your web document root with the following content. Change the $to_email with your recipient email address, $subject, and $body as per your need, Keep it as it is for testing purposes, $from_email with a sender email address:

nano send-email.php

Add the following sample PHP code for sending emails:

<?php
   $to_email = "recipient@idroot.us";
   $subject = "Simple Email Test via PHP";
   $body = "Hi,\n This is test email send by PHP Script";
   $headers = "From: sender@idroot.us";
   if ( mail($to_email, $subject, $body, $headers)) {
      echo("Email successfully sent to $to_email...");
   } else {
      echo("Email sending failed...");
   }
?>

Save and close the file, then test it by access in a web browser or simply execute it from the command line like below:

php send-email.php

Output:

Email successfully sent to recipient@idroot.us

Congratulations! You have successfully installed Sendmail. Thanks for using this tutorial for installing the Sendmail on Ubuntu 22.04 LTS Jammy Jellyfish system. For additional help or useful information, we recommend you check the official Sendmail website.