quform_pre_send_notification

add_action('quform_pre_send_notification_1_1', function ($mailer, Quform_Notification $notification, Quform_Form $form) {
    // Custom code
}, 10, 3);

function my_pre_send_notification($mailer, Quform_Notification $notification, Quform_Form $form)
{
    // Custom code
}
add_action('quform_pre_send_notification_1_1', 'my_pre_send_notification', 10, 3);

add_action('quform_pre_send_notification', function ($mailer, Quform_Notification $notification, Quform_Form $form) {
    // Custom code
}, 10, 3);

function my_pre_send_notification($mailer, Quform_Notification $notification, Quform_Form $form)
{
    // Custom code
}
add_action('quform_pre_send_notification', 'my_pre_send_notification', 10, 3);