> ## Documentation Index
> Fetch the complete documentation index at: https://docs.trysetter.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Audience Filtering

> Narrow a scheduled campaign send to a real-time list of leads from your side

For the endpoint spec (URL, auth, request/response shapes, examples), see [Filter Send Audience](/campaigns/filter-audience).

This page covers when to use audience filtering, how to configure it on a send, and the rules that apply when the filter event lands.

## Why

Most sends go to your full uploaded audience. Sometimes you want to **narrow a specific send** based on signals that aren't known at upload time — e.g. *"for tomorrow's send, only message leads who completed step X by tonight."*

Audience filtering lets your system POST a list of leads to **include** or **exclude** for a specific send, up until 5 minutes before that send fires.

## Enabling on a send

When adding a send to your campaign sequence, toggle **"Apply filter from inbound webhook"** on. The send will then accept filter events at the audience-filter endpoint until its filter deadline (5 min before its scheduled time).

A send with the filter off ignores any incoming filter events targeting it.

## Authentication setup

Pick the auth mode for inbound endpoints once per organization, in **Settings → Webhooks**:

* **API key** (default) — bearer-token auth using any active org-level API key.
* **HMAC** — generate a signing key, sign the raw request body with HMAC-SHA256, send as `X-Setter-Signature: sha256=<hex>`. Multiple signing keys can be active concurrently for rotation.

The same auth setting applies to all inbound endpoints for your org (audience filtering, lead events, etc.).

## When the filter is applied

The send's recipient list is materialized about 60 seconds before `scheduledFor`. At that moment, the materializer:

1. Loads every lead in the campaign's audience whose ingest status is `ok`
2. Drops opted-out phone numbers
3. If the send has the audience filter enabled, applies the **most recent** filter event for that send: `include` keeps only listed leads; `exclude` removes them
4. Inserts one row per remaining lead into the per-recipient send queue

So if you POST multiple filter events before the deadline, only the latest one matters.

## Lead matching

A lead in your filter payload matches an audience lead if **either** of these is true:

* The payload's `externalId` matches the audience lead's `external_id` column from the CSV (case-sensitive).
* The payload's `phoneE164` matches the normalized E.164 stored on the audience lead.

Leads in your filter payload that don't match any audience lead are silently ignored (logged).

## Combining with the event filter

A send can have **both** an audience filter (this page) **and** an event filter (matching against [Send Lead Event](/campaigns/send-lead-event)) configured. Both must keep a recipient for them to receive the message — the filters are ANDed.