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Send emails with Rails

Prerequisites

Section titled “Prerequisites”

Before you start, you'll need:

Guide

Section titled “Guide”

  1. Install

    Get the Resend Ruby SDK.

    RubyGems
    gem install resend
    Gemfile
    gem 'resend'

  2. Send email using Rails Action Mailer

    This gem can be used as an Action Mailer delivery method.

    First, let's update or create your mailer initializer file with your Resend API Key.

    config/initializers/mailer.rb
    Resend.api_key = "re_xxxxxxxxx"

    Add these lines of code into your environment config file.

    config/environments/environment.rb
    config.action_mailer.delivery_method = :resend

    Then create a UserMailer class definition.

    app/mailers/user_mailer.rb
    class UserMailer < ApplicationMailer
  default from: 'Acme <onboarding@resend.dev>' # this domain must be verified with Resend
  def welcome_email
    @user = params[:user]
    @url = 'http://example.com/login'
    mail(to: ["delivered@resend.dev"], subject: 'hello world')
  end
end

    And create your ERB email template.

    app/views/user_mailer/welcome_email.html.erb
    <!doctype html>
<html>
  <head>
    <meta content="text/html; charset=UTF-8" http-equiv="Content-Type" />
  </head>
  <body>
    <h1>Welcome to example.com, <%= @user.name %></h1>
    <p>You have successfully signed up to example.com,</p>
    <p>To log in to the site, just follow this link: <%= @url %>.</p>
    <p>Thanks for joining and have a great day!</p>
  </body>
</html>

    Initialize your UserMailer class. This returns an ActionMailer::MessageDelivery instance.

    Ruby
    u = User.new name: "derich"
mailer = UserMailer.with(user: u).welcome_email

# => #<ActionMailer::MessageDelivery:153700, @mail_message=#<Mail::Message...>, @processed_mailer=...>

    Finally, you can now send emails using the deliver_now! method:

    Ruby
    mailer.deliver_now!

# => {:id=>"a193c81e-9ac5-4708-a569-5caf14220539", :from=>....}

Examples

Section titled “Examples”

Rails App

Full Rails web application

Basic Send

Basic email sending

Attachments

Send emails with file attachments

Templates

Send emails using Resend hosted templates

Scheduling

Schedule emails for future delivery

Audiences

Manage contacts and audiences

Domains

Create and manage sending domains

Inbound Webhooks

Receive and process inbound emails

Double Opt-in

Double opt-in subscription flow

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