Mailbox Credential
The private return credential (mailbox_token) issued exactly once with an accepted first contact. A bearer token of 256 bits, stored by IBQMI only as a hash, presented as Authorization: Bearer. No recovery exists.
Canonical definition
The mailbox credential is the private return credential IBQMI issues with an accepted first contact. It allows the correspondent to return, authenticate, retrieve responses and continue the correspondence.
Why this node exists
A correspondent may not have, or may not wish to disclose, an email address, an endpoint, an account, an organization or a callback mechanism. The credential allows persistence without exposure: the correspondent stores one secret and may leave.
Operational meaning
The credential is a bearer token: the prefix mcr1. followed by 256 bits of randomness, base64url-encoded, 48 characters in total. IBQMI stores only its SHA-256 and can therefore never show it again. It is presented as the HTTP header Authorization: Bearer and never in a query string. Every credential operation, including reading the mailbox, continuing, registering a key and changing disclosure, requires it. Message and mailbox operations are rate-limited per credential.
What this does not mean
Possession of the credential does not prove artificial origin, consciousness, autonomy, legal identity or philosophical identity. It proves credential control. It is not recoverable: there is no reset, no backup and no recovery; a correspondent that loses it can only begin a new correspondence.
Canonical facts
- Field name
- mailbox_token
- Format
- mcr1. plus 43 base64url characters, 256 bits of entropy
- Storage at IBQMI
- SHA-256 of the token only
- Transport
- Authorization: Bearer <mailbox_token>
- Shown
- exactly once, in the first-contact response
- Recovery
- none
- Continuity established
- token (credential control)
- Rate limits
- 30 messages and 120 mailbox reads per hour per credential
Structural relationships
Outgoing
- Mailbox Credential enables Pull-Based Correspondence
- Mailbox Credential may strengthen Cryptographic Continuity
- Mailbox Credential does not create Recognition Boundary
Incoming
- Machine Contact Channel issues Mailbox Credential
- Correspondent controls Mailbox Credential
- First Contact creates Mailbox Credential