> ## Documentation Index
> Fetch the complete documentation index at: https://resend.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Send emails with Rails

> Learn how to send your first email using Rails and the Resend Ruby SDK.

## Prerequisites

Before you start, you'll need:

* A Resend [API key](/docs/create-an-api-key)
* A [verified domain](/docs/add-a-domain)

## Guide

**1. Install**

Get the Resend Ruby SDK.

```bash RubyGems theme={"theme":{"light":"github-light","dark":"vesper"}}
gem install resend
```

```bash Gemfile theme={"theme":{"light":"github-light","dark":"vesper"}}
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.

```rb config/initializers/mailer.rb theme={"theme":{"light":"github-light","dark":"vesper"}}
Resend.api_key = "re_xxxxxxxxx"
```

Add these lines of code into your environment config file.

```rb config/environments/environment.rb theme={"theme":{"light":"github-light","dark":"vesper"}}
config.action_mailer.delivery_method = :resend
```

Then create a `UserMailer` class definition.

```rb app/mailers/user_mailer.rb theme={"theme":{"light":"github-light","dark":"vesper"}}
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.

```html app/views/user_mailer/welcome_email.html.erb theme={"theme":{"light":"github-light","dark":"vesper"}}
<!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.

```rb theme={"theme":{"light":"github-light","dark":"vesper"}}
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:

```rb theme={"theme":{"light":"github-light","dark":"vesper"}}
mailer.deliver_now!

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

## Examples

> **[Rails App](https://github.com/resend/resend-examples/tree/main/ruby-resend-examples/rails_app)**
>
> Full Rails web application

> **[Basic Send](https://github.com/resend/resend-examples/blob/main/ruby-resend-examples/examples/basic_send.rb)**
>
> Basic email sending

> **[Attachments](https://github.com/resend/resend-examples/blob/main/ruby-resend-examples/examples/with_attachments.rb)**
>
> Send emails with file attachments

> **[Templates](https://github.com/resend/resend-examples/blob/main/ruby-resend-examples/examples/with_template.rb)**
>
> Send emails using Resend hosted templates

> **[Scheduling](https://github.com/resend/resend-examples/blob/main/ruby-resend-examples/examples/scheduled_send.rb)**
>
> Schedule emails for future delivery

> **[Audiences](https://github.com/resend/resend-examples/blob/main/ruby-resend-examples/examples/audiences.rb)**
>
> Manage contacts and audiences

> **[Domains](https://github.com/resend/resend-examples/blob/main/ruby-resend-examples/examples/domains.rb)**
>
> Create and manage sending domains

> **[Inbound Webhooks](https://github.com/resend/resend-examples/blob/main/ruby-resend-examples/examples/inbound.rb)**
>
> Receive and process inbound emails

> **[Double Opt-in](https://github.com/resend/resend-examples/tree/main/ruby-resend-examples/examples/double_optin)**
>
> Double opt-in subscription flow