how to _certainly_ block disposition notification / return receipt in Mail.app

Hello, I thought that Mail.app would not send auto-replies for any email (even more junk mail), and this has been said in multiple posts. However, it seems Mail.app has done it today, it has sent a notification to a spammer email, which did not exist and so I got notified back of such behaviour. It is an outlook server, but the problem should not be there: such server was configured to ask whether to send the disposition-notification-to or the return-receipt-to, so it should not send without my consent. while it just sent the notification back without my permission. The issue is that this is done even if you do not want to read the email... there must be a way of blocking that (note, my server was already configured not to send the receipt/notification without asking me, but it did anyway). It can be that Mail.app sends a consent to the server without asking me! Any clarifications and suggestions are welcome. (Just junking the email is not enough, it is not about detecting the cases, but also about being able to deal with them properly.)