---
title: "Add labels to an inbox thread"
method: POST
path: "/email_inboxes/{inbox_id}/threads/{thread_id}/labels"
tags: ["Email Inboxes"]
---

# Add labels to an inbox thread

`POST /email_inboxes/{inbox_id}/threads/{thread_id}/labels`

Adds one or more mutable labels to a thread, letting an agent mark a
whole conversation (for example `needs_review`) without labelling each
message individually.

Thread labels are independent of message labels: labelling a thread
does not label its messages, and labelling a message does not label its
thread. Idempotent and case-sensitive.

## Path parameters

- `inbox_id` string, uuid, required
- `thread_id` string, uuid, required

## Request body

- LabelMutationRequest — Labels to add or remove. Both operations are idempotent set operations, so a retried request converges instead of failing.
  - `labels` string[], required — One or more labels. Each label is a freeform, case-sensitive string of at most 255 characters; a message or thread may carry at most 50 labels. The `telnyx:` prefix is a reserved system namespace and is rejected on customer writes.

## Response `200`

The thread identity and its current label set.

- object
  - `data` object, required
    - `id` string, uuid, required
    - `record_type` 'email_thread', required
    - `inbox_id` string, uuid
    - `labels` string[], required

## Other responses

- `401` — Not authorized (10006).
- `404` — Resource not found (10001).
- `422` — Validation Failed (10015) or changeset validation error.
- `503` — Inbound label storage is temporarily unavailable.

---

[API](https://skmtc.net/team-telnyx/apis/telnyx-api-2.md) · [All operations](https://skmtc.net/team-telnyx/apis/telnyx-api-2/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/team-telnyx/telnyx-api-2/versions/8f5f4e537994/schema)