In instances where a letter cannot be delivered—such as due to an invalid address or the recipient being untraceable—Swiss Post will classify it as “Undeliverable” within the tracking system and will subsequently proceed with its destruction.
The status will automatically change from “Printed & Sent to Post” to “Undeliverable”.
Recommendation:
We advise regularly monitoring the tracking system to promptly confirm whether all your letters have been successfully delivered or if any have been designated as undeliverable.