generated: '2026-08-13'
method: searched
source: >-
  https://mailchimp.com/developer/release-notes/,
  https://mailchimp.com/developer/marketing/docs/fundamentals/,
  https://mailchimp.com/developer/transactional/docs/fundamentals/,
  https://status.mailchimp.com/, plus the version and basePath declared in the two
  first-party specifications harvested 2026-08-13
  (openapi/mailchimp-marketing-api-openapi-original.json,
  openapi/mailchimp-transactional-api-openapi-original.json).
description: >-
  Versioning, deprecation, and operational-lifecycle posture for the Mailchimp
  Marketing API (v3, URI-path versioned) and the Transactional/Mandrill API.
  Mailchimp versions by major URI path, revises the contract continuously under
  that path (the Marketing spec self-reports a three-part version), and announces
  changes via dated release notes. It publishes a deprecation POSTURE — old major
  versions stay reachable, are declared unsupported, and shut-off dates are
  promised in advance — but it does not implement RFC 8594 Sunset/Deprecation
  headers, so nothing about deprecation is machine-readable.
versioning:
  - api: mailchimp:mailchimp-marketing-api
    scheme: uri-path
    current: '3.0'
    contract_version: 3.0.91
    contract_version_checked: '2026-08-13'
    contract_url: https://api.mailchimp.com/schema/3.0/Swagger.json?expand
    host: https://<dc>.api.mailchimp.com/3.0
    docs: https://mailchimp.com/developer/marketing/docs/fundamentals/
    notes: >-
      The <dc> segment is the datacenter suffix derived from the API key (part
      after the dash) or the OAuth metadata endpoint. The URI path stays 3.0 while
      the published contract moves (3.0.55 when this repo was first harvested in
      May 2026; 3.0.91 on 2026-08-13) — an integrator cannot pin a minor version
      from the path.
  - api: mailchimp:mailchimp-transactional-api
    scheme: uri-path
    current: '1.0'
    contract_version: 1.4.1
    contract_basePath: /api/1.3
    contract_version_checked: '2026-08-13'
    contract_url: https://raw.githubusercontent.com/mailchimp/mailchimp-client-lib-codegen/main/spec/transactional.json
    host: https://mandrillapp.com/api/1.0
    docs: https://mailchimp.com/developer/transactional/docs/fundamentals/
    discrepancy: >-
      The documentation states "All API URLs listed in this documentation are
      relative to https://mandrillapp.com/api/1.0/" while the first-party spec
      declares basePath /api/1.3 and info.version 1.4.1. Both paths are live.
      Recorded 2026-08-13 as a documentation/contract divergence, not resolved —
      an integrator should pin whichever their client library uses.
deprecation:
  policy_url: https://mailchimp.com/developer/marketing/docs/fundamentals/
  policy_anchor: '#api-versions'
  changelog: https://mailchimp.com/developer/release-notes/
  sunset_header: false
  deprecation_header: false
  statement: >-
    "The first versions of the Marketing API, versions 1.1, 1.2, and 1.3, are no
    longer available. The previous version 2.0 has not been shut off, but is
    deprecated and unsupported. We'll announce shut off dates in advance, but we
    recommend migrating to version 3.0 since version 2.0 is not regularly tested
    or maintained."
  statement_source: https://mailchimp.com/developer/marketing/docs/fundamentals/
  statement_checked: '2026-08-13'
  grade: prose-only
  notes: >-
    This is the whole of Mailchimp's published deprecation policy: a paragraph in
    the fundamentals page plus dated release notes. There is no notice-period
    commitment in days, no sunset schedule, no RFC 8594 Sunset/Deprecation
    response headers, and no `deprecated: true` flag on any operation in either
    specification. An agent cannot detect a deprecation at runtime. Notable
    historical changes announced in the release notes: TLS 1.0/1.1 retired
    (2023-07-18, TLS 1.2+ required); invalid template name returns 404 instead of
    500 (2023-06-17); sending-domain authentication (DKIM/DMARC) enforced
    2024-03-15; webhook retries increased to 20 attempts (2024-06-17).
sla:
  url: https://mailchimp.com/legal/api_use/
  public_uptime_target: null
  notes: No public numeric uptime SLA is published for the developer APIs.
status_page: https://status.mailchimp.com/
status_notes: >-
  Transactional (Mandrill) status was added to the Mailchimp status page on
  2025-08-19.
deprecated_operations: []
deprecated_operations_note: >-
  Neither first-party specification marks any operation `deprecated: true`
  (checked 2026-08-13 across 298 Marketing and 99 Transactional operations).
sdk_decay:
  finding: >-
    The four official MARKETING client libraries have not been republished since
    2022-11-02 (3.0.80) while the API contract has moved to 3.0.91. The
    Transactional libraries are current at 1.4.1 (2026-03-24). See
    packages/mailchimp-packages.yml.
deprecated_products:
  - name: Mailchimp Open Commerce (Reaction Commerce)
    status: discontinued
    notes: >-
      The open-source GraphQL commerce stack (formerly Reaction Commerce) has
      been discontinued; documentation remains available but the project is no
      longer maintained.