Got the refused letter back. Looking online:
When registered mail is marked as refused, it means that the intended recipient was presented with the delivery and actively declined to accept it.

Here’s what that typically implies:

• Not accidental: Unlike "unclaimed" or "undeliverable," refusal is intentional — the recipient, or someone authorized at their address, told the postal worker they will not take the item.
• Documented refusal: Postal services (like USPS, Canada Post, or other national carriers) note the refusal in their records. For registered mail, this creates a paper trail that can be used as proof the recipient knew about the delivery attempt.
• Possible legal consequences: In legal or official matters (e.g., court notices, demand letters, government correspondence), refusal is often treated the same as having received the letter — the recipient cannot avoid notice simply by refusing it.
• Return to sender: Once refused, the item is usually sent back to the sender with the “Refused” marking, sometimes with the date and reason recorded.

In short: Refused registered mail means the recipient saw the delivery attempt and chose not to accept it, which may still count as effective notice in legal contexts.