refactor: adress review comments

lib/mv_web/emails/join_confirmation_email.ex

@@ -4,7 +4,7 @@ defmodule MvWeb.Emails.JoinConfirmationEmail do
   """
   use Phoenix.Swoosh,
     view: MvWeb.EmailsView,
-    layout: {MvWeb.EmailLayoutView, :layout}
+    layout: {MvWeb.EmailLayoutView, "layout.html"}
 
   use MvWeb, :verified_routes
   import Swoosh.Email
@@ -16,18 +16,28 @@ defmodule MvWeb.Emails.JoinConfirmationEmail do
   Sends the join confirmation email to the given address with the confirmation link.
 
   Called from the domain after a JoinRequest is created (submit flow).
+  Returns `{:ok, email}` on success, `{:error, reason}` on delivery failure.
+  Callers should log errors and may still return success for the overall operation
+  (e.g. join request created) so the user is not shown a generic error when only
+  the email failed.
   """
   def send(email_address, token) when is_binary(email_address) and is_binary(token) do
     confirm_url = url(~p"/confirm_join/#{token}")
     subject = gettext("Confirm your membership request")
 
+    assigns = %{
+      confirm_url: confirm_url,
+      subject: subject,
+      app_name: Mailer.mail_from() |> elem(0),
+      locale: Gettext.get_locale(MvWeb.Gettext)
+    }
+
     new()
     |> from(Mailer.mail_from())
     |> to(email_address)
     |> subject(subject)
     |> put_view(MvWeb.EmailsView)
-    |> put_layout({MvWeb.EmailLayoutView, "layout.html"})
-    |> render_body("join_confirmation.html", %{confirm_url: confirm_url, subject: subject})
-    |> Mailer.deliver!()
+    |> render_body("join_confirmation.html", assigns)
+    |> Mailer.deliver()
   end
 end