How can one send something with official documentation it has been recieved by the addressee?

Does anyone knowwhat company/government entity is required to send a letter and have an official document upon the receiving person signing for it? this must be able to stand up in court in that the name.of the person signing for it is in the document showing.it was recieved.

customer hasn’t paid in over a year so need to send letter and prove it was recieved by that person.

Registered post office is a no go because too many times they let anyone sign for it, and I can never get official documentation as to the person that signed for it, only that it “was recieved”. which is problematic because in court there is no proof THAT person recieved it, just that someone recieved it. Have had the same situation with curriers (HTC, Kerry, of, black cat etc). this creates the obvious issue of deniability by the defendant.

Is there such a service that a letter can be mailed (note, not delivered by the police or other such entity that would cause the person to reject signing it)and one can get an actual official stamp saying “recieved by XYZ person”?

also note, I already have email and line backups, as well as receipts we paid tax on, but that isnt enough in court as it is easily doctored and skewed. need third party verification to really avoid wasting time.

Don’t you have their stamp or signature on the original invoice?

No, they are monthly payments. I know it’s a good idea, and bigger b2b this is common. but wholesale to retail stores this isnt very common and hard to ask for sometimes.