generated: '2026-08-12'
method: searched
source: https://products.zetaglobal.com/sailthru/Content/developers/api-basics/technical.html
docs:
- https://products.zetaglobal.com/sailthru/Content/developers/api-basics/technical.html
- https://products.zetaglobal.com/sailthru/Content/developers/api-basics/responses.html
- https://products.zetaglobal.com/sailthru/Content/developers/api-basics/postbacks.html
api: sailthru:sailthru-api
note: >-
  Cross-cutting request/response semantics for the Sailthru API, read from the
  developer documentation. Sailthru is an RPC-over-HTTP design from the late
  2000s: the resource is the path segment, the verb carries the intent, and
  every payload — including complex nested objects — travels as form-encoded
  parameters rather than a JSON request body. Several conventions modern
  agents rely on are simply absent, and are recorded as such below rather
  than inferred.
request:
  style: rpc-over-http
  base_url: https://api.sailthru.com
  path_form: /<endpointName>
  methods: [GET, POST, DELETE]
  get_params: query string
  post_params: request body, application/x-www-form-urlencoded
  delete_params: query string
  json_body: false
  json_in_params: >-
    Structured arguments are passed as JSON-encoded values inside form
    parameters, not as a JSON request body.
  encoding: UTF-8
  https_required: true
  tls: TLS 1.2+; SSL not supported
authentication:
  style: api-key plus MD5 request signature
  parameters: [api_key, sig, format]
  detail: authentication/sailthru-authentication.yml
content_negotiation:
  mechanism: format parameter
  values: [json, xml]
  accept_header_honored: false
  note: >-
    Serialization is selected by a signed request parameter, not an Accept
    header — so an agent that negotiates by header will not get what it asked
    for. A format mismatch surfaces as HTTP 406.
idempotency:
  supported: false
  header: null
  note: >-
    Sailthru documents no idempotency key, no request-replay window and no
    deduplication contract on any endpoint, including POST /send. Retrying a
    send after a timeout risks a duplicate message. No Idempotency pointer is
    wired in apis.yml because the contract does not exist.
pagination:
  style: limit-only, per-endpoint
  cursor: false
  offset: false
  parameters:
  - name: limit
    endpoints: [/blast]
    description: >-
      Maximum number of records to return when requesting by status; set to 0
      to return all results.
  note: >-
    There is no cross-cutting pagination convention. Most read endpoints
    return the whole result set, and bulk extraction is handled by the
    asynchronous Job API (job-queries, job-content, job-update) rather than by
    paging.
bulk:
  mechanism: Job API
  endpoints: [/job]
  variants: [job-update, job-content, job-queries]
  style: asynchronous, poll for job status
field_expansion:
  supported: false
  note: >-
    The User API uses a `fields` parameter to opt into optional blocks of the
    profile rather than a generic expansion/sparse-fieldset syntax.
metadata:
  supported: true
  mechanism: user vars and profile fields
  note: >-
    Arbitrary custom data is stored as "vars" on user, content and purchase
    objects; key names are capped at 32 characters (API error 99 on overflow).
request_tracing:
  request_id_header: null
  note: No request-id or correlation header is documented on responses.
versioning:
  scheme: none
  current: null
  note: >-
    The API is unversioned — there is no version segment in the path, no
    version header and no version parameter. Changes ship through the product
    release notes; see changelog/sailthru-changelog.yml.
errors:
  envelope: {fields: [error, errormsg]}
  rfc9457: false
  detail: errors/sailthru-error-codes.yml
rate_limits:
  signaled: true
  headers: [X-Rate-Limit-Limit, X-Rate-Limit-Remaining, X-Rate-Limit-Reset]
  exhaustion: {http_status: 429, api_error: 43}
  detail: rate-limits/sailthru-rate-limits.yml
events:
  mechanism: API postbacks
  detail: asyncapi/sailthru-postbacks-webhooks.yml
templating:
  language: Zephyr
  docs: https://products.zetaglobal.com/sailthru/Content/developers/zephyr-syntax/syntax-overview.html
  note: >-
    Sailthru ships its own template/expression language, Zephyr, used inside
    email and on-site content. It is part of the developer contract but is not
    an HTTP API surface.