Add support for replyto parameter with SendGrid (#254)

* add reply_to param for sendgrid

* add tests for replyto

* better documentation

* remove unecessary line

* minor cleanup in sendgrid  adapter and test

* change SendgridAdapter to SendGridAdapter

* improve module doc for SendGridAdapter

lib/bamboo/adapters/send_grid_adapter.ex

@@ -5,6 +5,11 @@ defmodule Bamboo.SendGridAdapter do
   Use this adapter to send emails through SendGrid's API. Requires that an API
   key is set in the config.
 
+  If you would like to add a replyto header to your email, then simply pass it in
+  using the header property or put_header function like so:
+
+      put_header("reply-to", "foo@bar.com")
+
   ## Example config
 
       # In config/config.exs, or config.prod.exs, etc.
@@ -110,6 +115,7 @@ defmodule Bamboo.SendGridAdapter do
     %{}
     |> put_from(email)
     |> put_to(email)
+    |> put_reply_to(email)
     |> put_cc(email)
     |> put_bcc(email)
     |> put_subject(email)
@@ -156,6 +162,11 @@ defmodule Bamboo.SendGridAdapter do
   defp put_text_body(body, %Email{text_body: nil}), do: body
   defp put_text_body(body, %Email{text_body: text_body}), do: Map.put(body, :text, text_body)
 
+  defp put_reply_to(body, %Email{headers: %{"reply-to" => reply_to}} = email) do
+    Map.put(body, :replyto, reply_to)
+  end
+  defp put_reply_to(body, _), do: body
+
   defp maybe_put_x_smtp_api(body, %Email{private: %{"x-smtpapi" => fields}} = email) do
     # SendGrid will error with empty bodies, even while using templates.
     # Sets a default `text_body` and 'html_body' if either are not specified,

lib/bamboo/email.ex

@@ -20,7 +20,7 @@ defmodule Bamboo.Email do
 
       defmodule MyApp.Email do
         import Bamboo.Email
-    
+
         def welcome_email(user) do
           new_email(
             from: "me@app.com",
@@ -39,7 +39,7 @@ defmodule Bamboo.Email do
 
       defmodule MyApp.Email do
         import Bamboo.Email
-    
+
         def welcome_email(user) do
           # Since new_email/1 returns a struct you can update it with Kernel.struct!/2
           struct!(base_email,
@@ -48,15 +48,15 @@ defmodule Bamboo.Email do
             text_body: "Welcome to the app",
             html_body: "<strong>Welcome to the app</strong>"
           )
-    
+
           # or you can use functions to build it up step by step
           base_email
           |> to(user)
           |> subject("Welcome!")
           |> text_body("Welcome to the app")
           |> html_body("<strong>Welcome to the app</strong>")
         end
-    
+
         def base_email do
           new_email(from: "me@app.com")
         end

test/lib/bamboo/adapters/send_grid_adapter_test.exs

@@ -144,6 +144,15 @@ defmodule Bamboo.SendGridAdapterTest do
       }}
   end
 
+  test "deliver/2 correctly formats reply-to from headers" do
+    email = new_email(headers: %{"reply-to" => "foo@bar.com"})
+
+    email |> SendGridAdapter.deliver(@config)
+
+    assert_receive {:fake_sendgrid, %{params: params}}
+    assert params["replyto"] == "foo@bar.com"
+  end
+
   test "raises if the response is not a success" do
     email = new_email(from: "INVALID_EMAIL")