In your case, automation actually didn't fail, it just didn't recognize your additional instruction. Probably, you could have just patched the address with an easily removable piece of tape and that would definitely trigger a human attention, and delivery would go where it should
Having a database in which every citizen's domicile is registered does have its occasional advantages.
Fair point. And that was the advice given to me by the postal service.
The sign is a flowchart, it says first, is this mail for a different address? If so, either redeliver it (duh) or write "Misdelivered" in bold leters and put it into any postbox.
If not, but you don't recognise the recipient, strike through the whole address in black pen and write clearly "Not at this address" then put it into the postbox.
This won't stop you getting more mail by the way, I still get letters labelled "Urgent" with the name of the previous owner years after I bought this place. But it does stop literally the same mail coming back since the OCR will reject the crossed out address -- it's just that the sender may not have any effective process for what to do when they get the mail back undeliverable.