---
title: "Validate every address on a list"
method: POST
path: "/api/v1/lists/{id}/validation-runs"
tags: ["Validation"]
---

# Validate every address on a list

`POST /api/v1/lists/{id}/validation-runs`

## Request

- Base URL: `https://api.sendly.now`
- URL: `https://api.sendly.now/api/v1/lists/{id}/validation-runs`
- Auth: one of:
  - HTTP bearer
  - API key in cookie `better-auth.session_token`
  - OAuth 2 (authorization code, authorization URL `https://app.sendly.now/api/auth/oauth2/authorize`, token URL `https://app.sendly.now/api/auth/oauth2/token`, scopes: `validation:write`)

Start a background run over every contact on the list and answer immediately with the run. Poll `GET /api/v1/validation-runs/{id}` for progress and read the verdicts from its `/results` page.

This VALIDATES and changes nothing: no membership is unsubscribed, no contact is deleted. What to do about an `undeliverable` address is your decision, and a run that acted on its own findings would be acting on a DNS lookup that can also answer `unknown`.

A second run while one is already in flight for the same list is refused with 409 rather than queued: two runs would bill the same addresses twice.

Requires the `validation:write` scope — Check whether email addresses can receive mail — this is billed per address.

## Path parameters

- `id` string, uuid, required: Resource id.

## Response `202`

The run, accepted and queued

- EmailValidationRunV1: One bulk validation run over a list.
  - `completed_at` string, date-time, nullable, required
  - `created_at` string, date-time, required
  - `deliverable_count` integer, required
  - `failure_reason` string, nullable, required: Set only on `failed`. Prose for an operator; never parse it.
  - `id` string, required
  - `list_id` string, nullable, required
  - `processed_count` integer, required: Addresses checked so far. There is deliberately no total: a list changes size while a run walks it, so a denominator captured up front would be wrong by the time you read it.
  - `risky_count` integer, required
  - `started_at` string, date-time, nullable, required
  - `status` 'pending' | 'running' | 'completed' | 'failed', required
  - `undeliverable_count` integer, required

## Other responses

- `401`: `invalid_api_key` or `invalid_session` — missing or invalid credentials.
- `403`: `scope_missing`, `project_access_denied`, or `project_disabled`.
- `404`: `resource_not_found` — no list with this id belongs to the authenticated project.
- `422`: `validation_error` — query, path, or body parameters did not match the schema.
- `429`: `rate_limited` — see `Retry-After` and the `RateLimit` headers.
- `500`: `internal_error`.

---

[API](https://skmtc.dev/sendly/apis/sendly-api.md) · [All operations](https://skmtc.dev/sendly/apis/sendly-api/llms.txt) · [OpenAPI document](https://skmtc.dev/sendly/apis/sendly-api/revisions/ce7cfb7f7c7e?raw)