diff --git a/test/mv_web/live/global_settings_live_test.exs b/test/mv_web/live/global_settings_live_test.exs
index 2edaf74..9059a5e 100644
--- a/test/mv_web/live/global_settings_live_test.exs
+++ b/test/mv_web/live/global_settings_live_test.exs
@@ -1,8 +1,19 @@
 defmodule MvWeb.GlobalSettingsLiveTest do
-  use MvWeb.ConnCase, async: true
+  use MvWeb.ConnCase, async: false
   import Phoenix.LiveViewTest
   alias Mv.Membership
 
+  @smtp_env_keys [
+    "SMTP_HOST",
+    "SMTP_PORT",
+    "SMTP_USERNAME",
+    "SMTP_PASSWORD",
+    "SMTP_PASSWORD_FILE",
+    "SMTP_SSL",
+    "MAIL_FROM_NAME",
+    "MAIL_FROM_EMAIL"
+  ]
+
   describe "Global Settings LiveView" do
     setup %{conn: conn} do
       user = create_test_user(%{email: "admin@example.com"})
@@ -124,6 +135,43 @@ defmodule MvWeb.GlobalSettingsLiveTest do
       {:ok, _view, html} = live(conn, ~p"/settings")
       assert html =~ "SMTP" or html =~ "E-Mail" or html =~ "Settings"
     end
+
+    @tag :ui
+    test "disables all SMTP inputs when SMTP_HOST is set", %{conn: conn} do
+      clear_smtp_env()
+      System.put_env("SMTP_HOST", "smtp.env-only.example")
+      on_exit(fn -> clear_smtp_env() end)
+
+      {:ok, view, _html} = live(conn, ~p"/settings")
+
+      assert has_element?(view, "#setting_smtp_host[disabled]")
+      assert has_element?(view, "#setting_smtp_port[disabled]")
+      assert has_element?(view, "#setting_smtp_ssl[disabled]")
+      assert has_element?(view, "#setting_smtp_username[disabled]")
+      assert has_element?(view, "#setting_smtp_password[disabled]")
+      assert has_element?(view, "#setting_smtp_from_email[disabled]")
+      assert has_element?(view, "#setting_smtp_from_name[disabled]")
+    end
+
+    @tag :ui
+    test "does not render SMTP save action when SMTP_HOST is set", %{conn: conn} do
+      clear_smtp_env()
+      System.put_env("SMTP_HOST", "smtp.env-only.example")
+      on_exit(fn -> clear_smtp_env() end)
+
+      {:ok, view, _html} = live(conn, ~p"/settings")
+      refute has_element?(view, "#smtp-form button", "Save SMTP Settings")
+    end
+
+    @tag :ui
+    test "shows explicit ENV-only mode hint when SMTP_HOST is set", %{conn: conn} do
+      clear_smtp_env()
+      System.put_env("SMTP_HOST", "smtp.env-only.example")
+      on_exit(fn -> clear_smtp_env() end)
+
+      {:ok, _view, html} = live(conn, ~p"/settings")
+      assert html =~ "SMTP is fully managed via environment variables"
+    end
   end
 
   describe "Authentication section when OIDC-only is enabled" do
@@ -190,4 +238,8 @@ defmodule MvWeb.GlobalSettingsLiveTest do
       end
     end
   end
+
+  defp clear_smtp_env do
+    Enum.each(@smtp_env_keys, &System.delete_env/1)
+  end
 end