Fix email headers

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/web/email/email.ex

@@ -5,7 +5,6 @@ defmodule Mobilizon.Web.Email do
 
   use Bamboo.Phoenix, view: Mobilizon.Web.EmailView
 
-  alias Ecto.UUID
   alias Mobilizon.{Config, Events}
   alias Mobilizon.Events.Event
   alias Mobilizon.Service.Export.ICalendar
@@ -19,27 +18,27 @@ defmodule Mobilizon.Web.Email do
     |> new_email()
     |> from({Config.instance_name(), Config.instance_email_from()})
     |> put_header("Reply-To", Config.instance_email_reply_to())
-    |> put_header("Date", date())
-    |> put_header("Message-Id", message_id())
+    |> maybe_put_date_header()
+    |> maybe_put_message_id()
     |> assign(:instance, instance)
     |> put_html_layout({EmailView, "email.html"})
     |> put_text_layout({EmailView, "email.text"})
   end
 
   # Generating an UUID randomly causes Bamboo.Test.assert_delivered_email/1 to fail
-  defp message_id do
+  defp maybe_put_message_id(email) do
     if Application.fetch_env!(:mobilizon, :env) == :test do
-      "TEST_ENV_MESSAGE_ID@#{Config.instance_hostname()}"
+      put_header(email, "Message-Id", "TEST_ENV_MESSAGE_ID@#{Config.instance_hostname()}")
     else
-      "#{UUID.generate()}@#{Config.instance_hostname()}"
+      email
     end
   end
 
-  defp date do
+  defp maybe_put_date_header(email) do
     if Application.fetch_env!(:mobilizon, :env) == :test do
-      "REMOVED FOR TESTING"
+      put_header(email, "Date", "REMOVED FOR TESTING")
     else
-      Timex.format!(DateTime.utc_now(), "{WDshort}, {D} {Mshort} {YYYY} {h24}:{m}:{s} {Z}")
+      email
     end
   end