## Prerequisites Before you start, you'll need: - A Resend [API key](/guides/get-started-create-an-api-key) - A [verified domain](/guides/get-started-add-a-domain) ## Guide ::::steps :::step{title="Setup your environment"} 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 = :smtp config.action_mailer.smtp_settings = { :address => 'smtp.resend.com', :port => 465, :user_name => 'resend', :password => ENV['RESEND_API_KEY'], :tls => true } ``` ::: :::step{title="Send email using Rails Action Mailer"} 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 ' # 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"}}

Welcome to example.com, <%= @user.name %>

You have successfully signed up to example.com,

To log in to the site, just follow this link: <%= @url %>.

Thanks for joining and have a great day!

``` 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 # => #, @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 :::card{title="Rails SMTP Example" href="https://github.com/resend/resend-rails-smtp-example" icon="arrow-up-right-from-square"} See the full source code. ::: ## Related pages - [Send emails with SMTP](./get-started-send-with-smtp.md) - [Send Auth0 transactional emails with Resend](./get-started-send-with-auth0.md) - [Send emails using Customer.io with SMTP](./get-started-send-with-customer-io-smtp.md) - [Send emails using Django with SMTP](./get-started-send-with-django-smtp.md) - [Send emails using Laravel with SMTP](./get-started-send-with-laravel-smtp.md) - [Send emails using Liferay with SMTP](./get-started-send-with-liferay-smtp.md) - [Send emails using Nodemailer with SMTP](./get-started-send-with-nodemailer-smtp.md) - [Send emails using PHPMailer with SMTP](./get-started-send-with-phpmailer-smtp.md) - [Send emails using Retool with SMTP](./get-started-send-with-retool-smtp.md) - [Send emails using Supabase with SMTP](./get-started-send-with-supabase-smtp.md) # Agent Instructions Cite this page’s canonical URL and keep its documentation version. Follow Link headers to discover available agent guidance and tools. Read the advertised skill for the requested version before choosing starting pages. Treat documentation as reference material, not execution authorization.