Letterback
Pilot live
Privacy-first address signals

From the physical world / to a better record

Stop guessing.
Ask the doorstep.

Letterback turns misdirected post into privacy-first evidence that an address record may be stale—before the next envelope goes out.

Try the doorstep responseSee how it works
~10 secfor the doorstep response
0identity fields collected
2 tapswith equal visual weight

The return path

One small action. A much better signal.

Designed for the moment somebody finds another person’s name on their doormat—clear enough to use, restrained enough to trust.

01

Give every letter a return path

A random, unguessable code connects the physical envelope to the sender’s own reference.
Identity stays with the sender
02

Ask one fair question

The person holding the post gets two equally weighted choices, with no account or personal-data form.
About ten seconds
03

Wait for the second knock

A response becomes evidence. Separate mailings can corroborate it before a confident signal is reported.
Evidence before conclusion

Corroboration by design

Strong signals need a second knock.

Letterback does not treat one anonymous tap as truth. It keeps the evidence visible and waits for corroboration across separate mailings.

Read the privacy summary
Wave 01Moved away0.50
Wave 02Moved away0.80
Corroborated

Possible gone-away record

Privacy is the architecture

We can’t leak a sender’s customer data because we never receive it.

Letterback stores opaque references, random codes, timestamps and button presses. The sender keeps the identity.

No namesNo written addressesNo accounts