server->get('SERVER_NAME'); $form['#submit'][] = 'standard_form_install_configure_submit'; } /** * Submission handler to sync the contact.form.feedback recipient. */ function standard_form_install_configure_submit($form, FormStateInterface $form_state) { $site_mail = $form_state->getValue('site_mail'); ContactForm::load('feedback')->setRecipients([$site_mail])->save(); }