fix: join confirmation mail configuration

lib/mv_web/live/join_live.ex

@@ -142,8 +142,22 @@ defmodule MvWeb.JoinLive do
     case build_submit_attrs(params, socket.assigns.join_fields) do
       {:ok, attrs} ->
         case Membership.submit_join_request(attrs, actor: nil) do
-          {:ok, _} -> {:noreply, assign(socket, :submitted, true)}
-          {:error, _} -> validation_error_reply(socket, params)
+          {:ok, _} ->
+            {:noreply, assign(socket, :submitted, true)}
+
+          {:error, :email_delivery_failed} ->
+            {:noreply,
+             socket
+             |> put_flash(
+               :error,
+               gettext(
+                 "We could not send the confirmation email. Please try again later or contact support."
+               )
+             )
+             |> assign(:form, to_form(params, as: "join"))}
+
+          {:error, _} ->
+            validation_error_reply(socket, params)
         end
 
       {:error, message} ->