> ## Documentation Index
> Fetch the complete documentation index at: https://developer.z-api.io/llms.txt
> Use this file to discover all available pages before exploring further.

# On send

> Webhook for sent message callbacks

## Overview

This is the webhook for sent message callbacks.

<Warning>
  Z-API does not accept webhooks that are not **HTTPS**.
</Warning>

***

## Update webhook

### Header

<ParamField path="instanceId" type="string" required>
  Your instance ID. Available in the Z-API panel under **Instances**.
</ParamField>

<ParamField path="token" type="string" required>
  Your Z-API instance token.
</ParamField>

### Body

<ParamField body="value" type="string" required>
  Delivery webhook URL
</ParamField>

### Request Body

```json theme={"theme":{"light":"github-light","dark":"poimandres"}}
{
  "value": "https://your-system-address.com/instance/YOUR_INSTANCE/delivery"
}
```

***

### Webhook Response

### Response Attributes

<ResponseField name="phone" type="string">
  Destination phone number of the message
</ResponseField>

<ResponseField name="zaapId" type="string">
  Message identifier within the conversation
</ResponseField>

<ResponseField name="messageId" type="string">
  Message identifier on WhatsApp
</ResponseField>

<ResponseField name="instanceId" type="string">
  Instance identifier
</ResponseField>

<ResponseField name="momment" type="integer">
  Moment when the event was triggered (timestamp in milliseconds)
</ResponseField>

<ResponseField name="type" type="string">
  Type of the instance event, in this case it will be `DeliveryCallback`
</ResponseField>

<ResponseField name="error" type="string">
  Present **only in error cases**. Contains the description of the error that occurred when sending the message. Check the full list of possible errors in [On Send callback examples](/en/webhooks/on-message-send-examples)
</ResponseField>

```json theme={"theme":{"light":"github-light","dark":"poimandres"}}
{
  "phone": "554499999999",
  "zaapId": "A20DA9C0183A2D35A260F53F5D2B9244",
  "messageId": "A20DA9C0183A2D35A260F53F5D2B9244",
  "instanceId": "instance.id",
  "momment": 1777494009341,
  "type": "DeliveryCallback"
}
```

***

## Response

### 200

```json theme={"theme":{"light":"github-light","dark":"poimandres"}}
{
  "value": true
}
```

### 405

Make sure you are correctly sending the method specification, that is, verify that you sent POST or PUT as specified at the beginning of this topic.

### 415

If you receive a 415 error, make sure to add the "Content-Type" header to your request, which in most cases is "application/json".