Ruby on Rails - Send Emails

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Action Mailer is the Rails component that enables applications to send and receive emails. The other email related component in the Rails framework is Action Mailbox, which deals with receiving emails.

Action Mailer

Action Mailer uses mailers classes and views to create and configure the email to be sent. Mailer class inherits from ActionMailer::Base. It is similar to controller classes, as it also has:

  • Instance variables
  • It can use layouts and partials
  • It has access to a params hash
  • It also defines actions and associated views in app/views

Let's start creating a new project using the following command -

rails new mailtest

This will create the required framework to proceed. Now, we will start with configuring the ActionMailer.

Action Mailer – Configuration

Follow the steps given below to complete your configuration before proceeding with the actual work –

Go to the config\environments folder of your project and open development.rb file and add the following line inside the Rails.application.configure do block.

config.action_mailer.delivery_method = :smtp

It tells ActionMailer that you want to use the SMTP server. You can also set it to be :sendmail if you are using a Unix-based operating system such as Mac OS X or Linux.

This configuration file has many configuration settings. Keep them unchanged, configure smtp setting as follows to use Gmail for sending email:

Rails.application.configure do
  # Other existing settings...

  # Configure mailer settings for Gmail SMTP
  config.action_mailer.delivery_method = :smtp
  config.action_mailer.smtp_settings = {
    address: "smtp.gmail.com",
    port: 587,
    domain: "gmail.com",
    authentication: "plain",
    enable_starttls_auto: true,
    user_name: "GMAIL_USERNAME",
    password: "GMAIL_PASSWORD"
  }
  config.action_mailer.perform_deliveries = true  # Ensure emails are actually sent
  config.action_mailer.raise_delivery_errors = true  # Show errors for debugging
end

Replace each hash value with proper settings for your Simple Mail Transfer Protocol (SMTP) server. You can take this information from your Internet Service Provider if you already don't know. You don't need to change port number 25 and authentication type if you are using a standard SMTP server.

Note that Gmail has strict security policies. To send emails from your app, you can enable Less Secure Apps access in your Google account. However this feature not available for accounts with 2 Factor Authentication. In such case, the preferred option is to use an App Password instead of your real password. You can generate it in your Google Account Security settings.

You may also change the default email message format. If you prefer to send email in HTML instead of plain text format, add the following line to the development.rb as well −

ActionMailer::Base.default_content_type = "text/html"

ActionMailer::Base.default_content_type could be set to "text/plain", "text/html", and "text/enriched". The default value is "text/plain".

The next step will be to generate a mailer.

Generate a Mailer

Use the following command to generate a mailer as follows –

rails generate mailer UserMailer

This will create a file user_mailer.rb in the app\mailer directory. Check the content of this file as follows −

class Emailer < ActionMailer::Base
end

Let's add the welcome_email method as follows −

class UserMailer < ApplicationMailer
  default from: " GMAIL_USERNAME"

  def welcome_email(user)
    @user = user
    mail(to: @user.email, subject: "Welcome to My Awesome Site!")
  end
end
  • default Hash − This is a hash of default values for any email you send from this mailer. In this case we are setting the :from header to a value for all messages in this class. This can be overridden on a per-email basis
  • mail − The actual email message, we are passing the :to and :subject headers in.

Create a file called welcome_email.html.erb in app/views/user_mailer/. This will be the template used for the email, formatted in HTML –

<h1>Welcome to example.com, <%= @user.name %></h1>
<p>
	You have successfully signed up to example.com,your username is: 
	<%= @user.email %>.<br>
</p>
      
<p>
	To login to the site, just follow this link: 
	<%= @url %>.
</p>
<p>Thanks for joining and have a great day!</p>

You can also create Plain text email view in app/views/user_mailer/welcome_email.text.erb:

Welcome to example.com, <%= @user.name %>
===============================================
You have successfully signed up to example.com,
Your username is: <%= @user.email %>.

To login to the site, just follow this link: <%= @url %>.
Thanks for joining and have a great day!

Calling the Mailer

First, let's create a simple User scaffold.

rails generate scaffold User name:string email:string

Then, run migrations:

rails db:migrate

This will create User model, UsersController class with new, create, edit, update, destroy, index, show actions and the corresponding views such as new.html.erb, edit.html.erb, etc.

Modify UsersController to Send Email on User Creation

Edit the Create action in app/controllers/users_controller.rb to send a welcome email after a user is created:

  def create
    @user = User.new(user_params)
    if @user.save
      UserMailer.welcome_email(@user).deliver_now  # Send email after user creation
      redirect_to @user, notice: "User was successfully created. A welcome email has been sent."
    else
      render :new, status: :unprocessable_entity
    end
  end

  private

  def user_params
    params.require(:user).permit(:name, :email)
  end

Ensure that the UsersController also has the show action as follows:

def show
   @user = User.find(params[:id])
end

The set_user method stores the current user in the @user instance variable.

That’s it. Now, to test your application start the server and visit  http://127.0.0.1:3000/users/new. It displays the following screen to add a new user

Modify UsersController

This adds a new User object and calls the welcome_email method to generate the welcome email, using the Gmail address set in the configuration.

While the user can verify that he has received the email, the app redirects the browser to show the confirmation.

welcome email

On the console, you get the following log:

UserMailer#welcome_email: processed outbound mail in 148.6ms
Delivered mail 67ee3031b5cd_73d463885c4@GNVBGL3.mail (22000.3ms)
Date: Thu, 03 Apr 2025 12:22:33 +0530
From: *****@gmail.com
To: *****@gmail.com
Message-ID: <67ee3031b5cd_73d463885c4@GNVBGL3.mail>
Subject: Welcome to My Awesome Site!
Mime-Version: 1.0
Content-Type: multipart/alternative;
  boundary="--==_mimepart_67ee3030ed242_73d4638841e";
  charset=UTF-8
Content-Transfer-Encoding: 7bit

----==_mimepart_67ee3030ed242_73d4638841e
Content-Type: text/plain;
  charset=UTF-8
Content-Transfer-Encoding: 7bit

For more information on how to send emails using Rails, please go through the official documentation on ActionMailer (https://guides.rubyonrails.org/action_mailer_basics.html)

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