The cost of sending a registered letter has become extortionate (as has the cost of postage in general). So I have started delivering documents by hand instead of using the post. I have my own database of numbers just like the post office. I print the unique number of the article on the article and also on a custom form for which the recipient must sign to receive.

For example, I print “livraison recommandée n°003” on the envelope and “Recommandé N°003” on the form they sign. Someone complained saying “this is not a recommandé”. My French is dysfunctional so I have no idea how I should be referring to this number. Is “recommandée” a word reserved for the post office? What phrase should I be using?

Should I just drop the “recommandée” and say “livraison n°003”? Sometimes instead of using my own form I use the post offices form which has on it “Recommandé N°”. Should I strike out “Recommandé” and write something else?

update

I tried context.reverso.net and found these translations in an effort to distinguish a “registered letter” from “recorded delivery”:

①
(en) Any claims must be presented within 30 days of the service provided by registered letter with recorded delivery.
→ (fr) Toute réclamation doit être adressée sous 30 jours après la prestation par courrier recommandé avec accusé de réception.

②
(en) All eventual complaints concerning the non-conformity of services in relation to contractual engagements may be indicated by registered mail with recorded delivery or email to Parc Résidentiel de Loisirs L'Escapade.
→ (fr) Toute réclamation éventuelle concernant la non-conformité des prestations par rapport aux engagements contractuels peut être signalée par courrier recommandé avec avis de réception ou e-mail au PRL L'ESCAPADE.

So I think “accusé de réception” or “d'avis de réception” is the phrase I need. Can any francophones confirm? Is one phrase better than the other?