Letterback
Pilot privacy summary
The less we know, the safer the signal.
Letterback is designed so the response service never needs the recipient's name or written address.
What this pilot records
A random envelope code, the answer selected, timestamps, a coarse device category and—when enabled—a short-lived keyed hash used to limit abuse.
What it does not collect
No recipient name, scanner name, written address, email, telephone number, account or raw IP address. The page sets no non-essential cookies.
How an answer is used
One anonymous answer is evidence, not an automatic instruction. Letterback looks for corroboration across separate mailings before reporting a confident address-quality signal.