Code for step 3

config/dev.exs

@@ -9,6 +9,8 @@ config :mjml_demo, MjmlDemo.Repo,
   show_sensitive_data_on_connection_error: true,
   pool_size: 10
 
+config :mjml_demo, MjmlDemo.Emails, adapter: Swoosh.Adapters.Local
+
 # For development, we disable any cache and enable
 # debugging and code reloading.
 #

lib/mjml_demo/emails.ex

@@ -0,0 +1,44 @@
+defmodule MjmlDemo.Emails do
+  use Swoosh.Mailer, otp_app: :mjml_demo
+
+  import Swoosh.Email
+
+  alias __MODULE__.ConfirmationInstructions
+
+  def confirmation_instructions(user, confirmation_url) do
+    # You'll want to update the User schema and the DB migration to support
+    # storing first+last names, plan tiers, and whatever else you want to
+    # associate to the user registration.
+    rendered_email =
+      ConfirmationInstructions.render(
+        first_name: "Agent",
+        last_name: "Smith",
+        confirmation_url: confirmation_url,
+        tier: "Gold"
+      )
+
+    new()
+    |> to(user.email)
+    |> from({"Onboarding Team", "welcome@saas-central.com"})
+    |> subject("Welcome to SaaS-Central!")
+    |> html_body(rendered_email)
+    |> text_body("""
+    Hello Agent Smith and thank you for signing up for the Gold plan!!!
+
+    You can confirm your account by visiting the following URL: #{confirmation_url}
+    """)
+    |> deliver()
+  end
+
+  def generate_template(file_path) do
+    {:ok, template} =
+      file_path
+      |> File.read!()
+      |> Mjml.to_html()
+
+    ~r/{{\s*([^}^\s]+)\s*}}/
+    |> Regex.replace(template, fn _, variable_name ->
+      "<%= @#{variable_name} %>"
+    end)
+  end
+end

lib/mjml_demo_web/router.ex

@@ -43,6 +43,14 @@ defmodule MjmlDemoWeb.Router do
     end
   end
 
+  if Mix.env() == :dev do
+    scope "/dev" do
+      pipe_through [:browser]
+
+      forward "/mailbox", Plug.Swoosh.MailboxPreview, base_path: "/dev/mailbox"
+    end
+  end
+
   ## Authentication routes
 
   scope "/", MjmlDemoWeb do