{
  "$schema": "/api/schemas/documents.schema.json",
  "apiVersion": "1.1.0",
  "lastModified": "2026-10-14T17:03:00.748Z",
  "sourcePath": "src/main/data/docs",
  "docId": "RFC7504",
  "document": {
    "abstract": "This memo defines two Simple Mail Transfer Protocol (SMTP) reply codes, 521 and 556. The 521 code was originally described in an Experimental RFC in 1995 and is in wide use, but has not previously been formally incorporated into SMTP. The 556 code was created to support the new tests and actions specified in RFC 7505. These codes are used to indicate that an Internet host does not accept incoming mail at all. This specification is not applicable when the host sometimes accepts mail but may reject particular messages, or even all messages, under specific circumstances.",
    "abstract$meta": {
      "confidence": "high",
      "note": "Parsed from RFC index XML abstract",
      "originalValue": null,
      "source": "parsed",
      "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
      "updated": "2026-10-14T16:14:32.874Z",
      "version": "extractDocs.js@commit:1ff63569c1a0"
    },
    "authors": [
      {
        "name": "Dr. John C. Klensin"
      }
    ],
    "authors$meta": {
      "confidence": "high",
      "note": "Parsed from Datatracker doc page article:author (profile full names)",
      "originalValue": null,
      "source": "parsed",
      "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
      "updated": "2026-10-14T16:14:32.874Z",
      "version": "extractDocs.js@commit:1ff63569c1a0"
    },
    "docId": "RFC7504",
    "docId$meta": {
      "confidence": "high",
      "note": "Derived from RFC number or Datatracker identifier",
      "originalValue": null,
      "source": "resolved",
      "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
      "updated": "2026-10-14T16:14:32.873Z",
      "version": "extractDocs.js@commit:1ff63569c1a0"
    },
    "docLabel": "IETF RFC 7504",
    "docLabel$meta": {
      "confidence": "high",
      "note": "Constructed from provider and document identifier",
      "originalValue": null,
      "source": "resolved",
      "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
      "updated": "2026-10-14T16:14:32.874Z",
      "version": "extractDocs.js@commit:1ff63569c1a0"
    },
    "docNumber": "7504",
    "docNumber$meta": {
      "confidence": "high",
      "note": "Parsed from RFC info page report metadata",
      "originalValue": null,
      "source": "parsed",
      "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
      "updated": "2026-10-14T16:14:32.874Z",
      "version": "extractDocs.js@commit:1ff63569c1a0"
    },
    "docTitle": "SMTP 521 and 556 Reply Codes",
    "docTitle$meta": {
      "confidence": "high",
      "note": "Parsed from RFC index XML title",
      "originalValue": null,
      "source": "parsed",
      "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
      "updated": "2026-10-14T16:14:32.874Z",
      "version": "extractDocs.js@commit:1ff63569c1a0"
    },
    "docType": "Standard",
    "docType$meta": {
      "confidence": "high",
      "note": "Mapped from Datatracker std_level or RFC status text",
      "originalValue": null,
      "source": "parsed",
      "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
      "updated": "2026-10-14T16:14:32.874Z",
      "version": "extractDocs.js@commit:1ff63569c1a0"
    },
    "doi": "10.17487/RFC7504",
    "doi$meta": {
      "confidence": "high",
      "note": "Parsed from RFC index XML doi",
      "originalValue": null,
      "source": "resolved",
      "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
      "updated": "2026-10-14T16:14:32.874Z",
      "version": "extractDocs.js@commit:1ff63569c1a0"
    },
    "href": "https://doi.org/10.17487/RFC7504",
    "href$meta": {
      "confidence": "high",
      "note": "Derived from DOI (https://doi.org/<doi>)",
      "originalValue": null,
      "source": "resolved",
      "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
      "updated": "2026-10-14T16:14:32.874Z",
      "version": "extractDocs.js@commit:1ff63569c1a0"
    },
    "keywords": [
      "Email"
    ],
    "keywords$meta": {
      "confidence": "high",
      "note": "Parsed from RFC index XML keywords",
      "originalValue": [
        "Reply Code",
        "Email",
        "No Mail"
      ],
      "overridden": true,
      "source": "parsed",
      "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
      "updated": "2026-10-14T17:03:00.748Z",
      "version": "extractDocs.js@commit:8aec15acefbb"
    },
    "pages": "7",
    "pages$meta": {
      "confidence": "high",
      "note": "Parsed from RFC index XML page-count",
      "originalValue": null,
      "source": "parsed",
      "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
      "updated": "2026-10-14T16:14:32.874Z",
      "version": "extractDocs.js@commit:1ff63569c1a0"
    },
    "publicationDate": "2015-06-01",
    "publicationDate$meta": {
      "confidence": "high",
      "note": "Parsed from RFC index XML date",
      "originalValue": null,
      "source": "parsed",
      "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
      "updated": "2026-10-14T16:14:32.874Z",
      "version": "extractDocs.js@commit:1ff63569c1a0"
    },
    "publisher": "IETF",
    "publisher$meta": {
      "confidence": "high",
      "note": "Static: provider",
      "originalValue": null,
      "source": "parsed",
      "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
      "updated": "2026-10-14T16:14:32.874Z",
      "version": "extractDocs.js@commit:1ff63569c1a0"
    },
    "references": {
      "bibliographic": [
        "RFC1846",
        "RFC7505"
      ],
      "bibliographic$meta": {
        "confidence": "medium",
        "flag": "MIXED_REF_LAYOUT_RISK anchored=5 proseBlocks=8 skippedAnchorBlocks=6",
        "note": "Parsed from RFC HTML references/informative sections",
        "originalValue": [],
        "reviewRequired": true,
        "source": "parsed",
        "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
        "updated": "2026-10-14T16:14:32.874Z",
        "version": "extractDocs.js@commit:1ff63569c1a0"
      },
      "normative": [
        "RFC2119",
        "RFC5321",
        "orphan/RFC7504/h:c8e7827a"
      ],
      "normative$meta": {
        "confidence": "high",
        "note": "Parsed from RFC HTML normative references sections",
        "originalValue": [],
        "source": "parsed",
        "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
        "updated": "2026-10-14T16:14:32.874Z",
        "version": "extractDocs.js@commit:1ff63569c1a0"
      }
    },
    "resolvedHref": "https://www.rfc-editor.org/info/rfc7504/",
    "resolvedHref$meta": {
      "confidence": "high",
      "note": "Final URL resolved via URL redirect verification",
      "originalValue": null,
      "source": "resolved",
      "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
      "updated": "2026-10-14T16:14:32.874Z",
      "version": "extractDocs.js@commit:1ff63569c1a0"
    },
    "status": {
      "active": true,
      "active$meta": {
        "confidence": "high",
        "note": "Derived from supersession relationship fields",
        "originalValue": null,
        "source": "resolved",
        "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
        "updated": "2026-10-14T16:14:32.874Z",
        "version": "extractDocs.js@commit:1ff63569c1a0"
      },
      "amends": [
        "RFC1846",
        "RFC5321"
      ],
      "amends$meta": {
        "confidence": "high",
        "note": "Parsed from RFC index XML",
        "originalValue": [],
        "source": "parsed",
        "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
        "updated": "2026-10-14T16:14:32.874Z",
        "version": "extractDocs.js@commit:1ff63569c1a0"
      },
      "errataExist": false,
      "errataExist$meta": {
        "confidence": "high",
        "note": "Derived from presence of errata links on RFC/Datatracker pages",
        "originalValue": null,
        "source": "parsed",
        "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
        "updated": "2026-10-14T16:14:32.874Z",
        "version": "extractDocs.js@commit:1ff63569c1a0"
      },
      "latestVersion": true,
      "latestVersion$meta": {
        "confidence": "high",
        "note": "Derived from supersession relationship fields",
        "originalValue": null,
        "source": "resolved",
        "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
        "updated": "2026-10-14T16:14:32.874Z",
        "version": "extractDocs.js@commit:1ff63569c1a0"
      },
      "statusNote": "Proposed Standard",
      "statusNote$meta": {
        "confidence": "high",
        "note": "Mapped from Datatracker doc.json std_level",
        "originalValue": null,
        "source": "parsed",
        "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
        "updated": "2026-10-14T16:14:32.874Z",
        "version": "extractDocs.js@commit:1ff63569c1a0"
      },
      "superseded": false,
      "superseded$meta": {
        "confidence": "high",
        "note": "Derived from supersession relationship fields",
        "originalValue": null,
        "source": "resolved",
        "sourceUrl": "https://www.rfc-editor.org/info/rfc7504/",
        "updated": "2026-10-14T16:14:32.874Z",
        "version": "extractDocs.js@commit:1ff63569c1a0"
      }
    }
  }
}