Upload a document for a contact

Upload one private PDF for one contact, then send it with document: { id } on a template with a DOCUMENT header.

Send multipart/form-data, not JSON: the PDF as the file part, the contact's id as contact_id, and optionally kind (a label such as invoice; statement when left out). The file's name is the filename the recipient sees.

PDF only, up to 4 MB (a request body is capped at 4.5 MB). The bytes decide what the file is, whatever its Content-Type says: a file without a PDF header and an end-of-file marker is refused with details.reason: "not_a_pdf", a larger one with file_too_large. Nothing is stored when it is refused.

The file is private: it has no URL. Send it with POST /api/v1/messages and document: { id }; it is fetched with a link that lasts an hour, at send time only. It counts toward your plan's storage, and it is kept for 90 days, like the dashboard's uploads: after that it is deleted, and a send by its id answers 404 not_found, document_not_found. Upload it again to send it later.

A document is only ever sent to the contact it was uploaded for. A contact this workspace does not hold answers 404 not_found; one outside a business-restricted key's businesses answers 403 forbidden.