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POST
Post a message to a document

Authorizations

Authorization
string
header
required

Personal API key, e.g. Authorization: Bearer sajn_sk_.... Not scope-limited — acts as the issuing user.

Headers

Sajn-Version
enum<string>

API version for this request. Without it, the request uses the organization's default version; an organization without a default is pinned to the latest version by its first request.

Available options:
2026-09,
2026-10
Idempotency-Key
string

Makes retries safe. A retry with the same key and the same request replays the stored response for 24 hours (header Idempotent-Replayed: true); the same key with a different request returns 400.

Maximum string length: 255

Path Parameters

id
string
required

The document ID.

Body

application/json

Body

body
string
required

The message text, up to 2,000 characters.

Required string length: 1 - 2000
internal
boolean
default:false

When true the message is internal (visible only to workspace members). When false (default) it is external — visible to the document signers and triggers their email notifications.

Response

200

id
string
required

The message ID.

documentId
string
required

The document ID.

body
string
required

The message text.

internal
boolean
required

true = internal (workspace-only); false = external (visible to signers, sends notifications)

createdAt
string<date-time>
required

When the message was created.

updatedAt
string<date-time>
required

When the message was last updated.

author
object | null
required

Who wrote the message. Null when the author no longer exists.