---
title: "Reverse email append"
method: POST
path: "/reverse-email-append"
tags: ["Enrichment"]
---

# Reverse email append

`POST /reverse-email-append`

## Request

- Base URL: `https://app.1lookup.io/api/v1`
- URL: `https://app.1lookup.io/api/v1/reverse-email-append`
- Auth: HTTP bearer

Returns the person, postal address, phone numbers and company behind an email address. Costs 10 credits, and nothing when there is no match.

## Request body

- object
  - `email` string, required: Email address to resolve.
  - `bypass_cache` boolean: Skip the 7-day result cache and run a fresh lookup. Also accepted as `bypassCache` or `forceFresh`, in the body or the query string. A cached result you ran yourself is free; a fresh lookup is charged as usual.

## Response `200`

Lookup completed. `metadata.credits_used` says what it cost.

- object
  - `success` true, required
  - `data` ReverseEmailResult, required: Reverse email append. `matched` is false when no record was found, and then nothing is charged.
    - `request` LookupRequest, required
      - `id` string, uuid, required: Id of this lookup.
      - `type` string, required: Lookup type, such as `phone`, `email` or `hlr_lookup`.
      - `input` string, required: The input as it was looked up, after normalization.
      - `timestamp` string, date-time, required: When the lookup ran.
      - `processing_time_ms` integer, required: Server-side processing time, in milliseconds.
    - `risk_assessment` RiskAssessment
      - `fraud_score` number: 0 to 100, higher is riskier. Not returned by every product (phone validation has none).
      - `risk_level` 'LOW' | 'MEDIUM' | 'HIGH' | 'CRITICAL', required
      - `risk_factors` string[], required: Codes for what raised the risk, such as `NOT_REACHABLE`, `DISPOSABLE_EMAIL` or `NO_MATCH_FOUND`.
      - `confidence_level` number, required: 0 to 100.
    - `classification` object, required
      - `matched` boolean, required
      - `email` string, nullable
      - `first_name` string, nullable
      - `last_name` string, nullable
      - `address` string, nullable
      - `city` string, nullable
      - `state` string, nullable
      - `zip_code` string, nullable
      - `country` string, nullable
      - `phone` string, nullable
      - `phone_dnc` boolean: The phone is on a Do Not Call list.
      - `cell` string, nullable
      - `cell_dnc` boolean: The cell is on a Do Not Call list.
      - `lookup_type` 'reverse_email'
    - `insights` object, required
      - `reverse_email_result` object
        - `matched` boolean
        - `contact` object
          - `fullName` string, nullable
          - `firstName` string, nullable
          - `lastName` string, nullable
        - `email` string, nullable
        - `phones` object
          - `phoneNumber` string, nullable
          - `phoneDnc` boolean
          - `cellNumber` string, nullable
          - `cellDnc` boolean
        - `address` object
          - `line1` string, nullable
          - `city` string, nullable
          - `state` string, nullable
          - `country` string, nullable
          - `zipCode` string, nullable
        - `company` object
          - `name` string, nullable
          - `jobTitle` string, nullable
          - `industry` string, nullable
          - `linkedInUrl` string, nullable
          - `website` string, nullable
          - `country` string, nullable
    - `recommendations` Recommendations, required
      - `primary_action` 'APPROVE' | 'VERIFY' | 'REVIEW' | 'BLOCK', required
      - `secondary_actions` string[], required
      - `user_message` string, required: One plain sentence describing the result.
      - `business_rules` object, required: Product-specific yes/no rules, such as `sms_allowed` and `voice_allowed` for a phone number.
    - `metadata` LookupMetadata, required
      - `api_version` string, required
      - `schema_version` string, required
      - `credits_used` integer: Credits this call cost. 0 for a no-match on success-billed products, and for a cached result you ran yourself.
      - `credits_remaining` integer: Credits left on the account after this call.
      - `cache_hit` boolean, required: True when the result came from the 7-day cache.
      - `cached_at` string, date-time: When the cached result was first looked up. Only on cache hits.
      - `data_sources` string[], required: Generic labels for the kinds of data consulted.
      - `fallback_used` boolean: Email verification only: a second verification ran.
      - `lookup_source` 'standard' | 'premium': Reverse phone lookup only: which record was read.

## Other responses

- `400`: `INVALID_REQUEST`: The body is not valid JSON; `MISSING_FIELD`: The request field is missing; `INVALID_INPUT`: The input is not a string, or does not match the expected format; `VALIDATION_FAILED`: The lookup could not be completed for this input. Nothing was charged; `UPSTREAM_ERROR`: The source could not answer for this input. Nothing was charged
- `401`: `UNAUTHORIZED`: Invalid or missing API key
- `402`: `INSUFFICIENT_CREDITS`: Not enough credits for the request
- `403`: `UPGRADE_REQUIRED`: The account has no paid plan, and API access needs one. Upgrade at https://app.1lookup.io/billing?tab=plan; `INSUFFICIENT_SCOPE`: The call was signed with an AI connector (MCP) sign-in, which can only reach /phone, /email, /ip and /account. Use an API key
- `429`: `RATE_LIMIT_EXCEEDED`: Too many requests
- `500`: `INTERNAL_ERROR`: Internal server error
- `503`: `SERVICE_UNAVAILABLE`: The lookup service, or the API key check, is temporarily unavailable. Nothing was charged; retry after `Retry-After` seconds; `SERVICE_BUSY`: The service is busy. Nothing was reserved or charged; retry after `Retry-After` seconds; `UPSTREAM_QUOTA_EXHAUSTED`: The lookup is temporarily unavailable on our side. Nothing was charged; retry after `Retry-After` seconds; `UPSTREAM_TIMEOUT`: The source took too long to answer. Nothing was charged; retry after `Retry-After` seconds

---

[API](https://skmtc.dev/1lookup/apis/1lookup-api.md) · [All operations](https://skmtc.dev/1lookup/apis/1lookup-api/llms.txt) · [OpenAPI document](https://skmtc.dev/1lookup/apis/1lookup-api/revisions/57b6d8ba04ac?raw)