diff --git a/test/test_helper.rb b/test/test_helper.rb
index 0a5ddb5d9..10f4f6e35 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -392,6 +392,11 @@ module Redmine
   end
 
   class IntegrationTest < ActionDispatch::IntegrationTest
+    def setup
+      ActionMailer::MailDeliveryJob.disable_test_adapter
+      super
+    end
+
     def log_user(login, password)
       User.anonymous
       get "/login"