The situation now is that he has not been served the papers. Send them again by first class post but take them to the post office counter and ask for proof of posting. The documents will then just dropped through his letterbox and will be validly served.
This is very common with recorded delivery documents in the deviation and is one of the reasons why there is no legal provision generally for documents to be served by recorded delivery.
Can I clarify anything for you?
Please rate the service positive. It doesn’t cost you anything but helped me greatly.
We can still exchange emails. Best wishes. FES.
Unless he boards up the letterbox, they will just drop onto his mat. If he then put them back in the post to you, marked “return to sender” or suchlike, he has still had the document as far as the court are concerned.
If the court will assist you, so much the better.