[Yandex Cloud documentation](../../../index.md) > [Yandex API Gateway](../../index.md) > [Step-by-step guides](../index.md) > Creating a trigger > Creating an email trigger

# Creating an email trigger that sends messages to WebSocket connections

Create an [email trigger](../../concepts/trigger/mail-trigger.md) to send messages to Yandex API Gateway [WebSocket connections](../../concepts/extensions/websocket.md) when an email arrives. The service automatically generates an email address when creating the trigger.

## Getting started {#before-you-begin}

To create a trigger, you will need:

* API gateway. Messages will be sent to WebSocket connections accessing the API gateway at the path specified in the trigger settings. If you do not have an API gateway, [create one](../api-gw-create.md).

    {% note info %}

    The trigger does not call the API gateway when sending messages to WebSocket connections.

    {% endnote %}

* [Service account](../../../iam/concepts/users/service-accounts.md) with the `api-gateway.websocketBroadcaster` role. If you do not have a service account, [create one](../../../iam/operations/sa/create.md).

* Optionally, a [bucket](../../../storage/concepts/bucket.md) to save email attachments to. If you do not have a bucket, [create one](../../../storage/operations/buckets/create.md) with restricted access.

## Creating a trigger {#trigger-create}

{% note info %}

The trigger is initiated within five minutes after it is created.

{% endnote %}

{% list tabs group=instructions %}

- Management console {#console}

    1. In the [management console](https://console.yandex.cloud), select the folder where you want to create a trigger.

    1. Navigate to **API Gateway**.

    1. In the left-hand panel, select ![image](../../../_assets/console-icons/gear-play.svg) **Triggers**.

    1. Click **Create trigger**.

    1. Under **Basic settings**:

        * Optionally, enter a trigger name and description.
        * In the **Type** field, select `Email`.
        * In the **Launched resource** field, select `API gateway`.
    
    1. Optionally, under **Settings for saving attachments**:
      
        * In the **Bucket** field, select the bucket to save email attachments to.
        * In the **Service account** field, specify a service account with permissions to upload objects to the Object Storage bucket.

    1. Under **Batch message settings**, specify:

        * Batch size. The values may range from 1 to 1,000. The default value is 1.
        * Maximum wait time. The values may range from 1 to 60 seconds. The default value is 1 second.

       The trigger groups messages within the specified wait time period and sends them to WebSocket connections. The number of messages cannot exceed the specified batch size.

    1. Under **API gateway settings**:
       * In the **API gateway** field, select the API gateway.
       * In the **Path** field, specify the path in the OpenAPI specification. Messages will be sent through WebSocket connections established using this path.
       * In the **Service account** field, select the [service account](../../../iam/concepts/users/service-accounts.md) to send messages to WebSocket connections.

    1. Click **Create trigger**.

- CLI {#cli}

    If you do not have the Yandex Cloud CLI yet, [install and initialize it](../../../cli/quickstart.md#install).

    The folder used by default is the one specified when [creating](../../../cli/operations/profile/profile-create.md) the CLI profile. To change the default folder, use the `yc config set folder-id <folder_ID>` command. You can also specify a different folder for any command using `--folder-name` or `--folder-id`. If you access a resource by its name, the search will be limited to the default folder. If you access a resource by its ID, the search will be global, i.e., through all folders based on access permissions.

    To create a trigger that sends messages to WebSocket connections, run this command:
    ```bash
    yc serverless trigger create mail \
      --name <trigger_name> \
      --batch-size <batch_size> \
      --batch-cutoff <maximum_wait_time> \
      --attachements-bucket <bucket_name> \
      --attachements-service-account-id <service_account_ID> \
      --gateway-id <API_gateway_ID> \
      --gateway-websocket-broadcast-path <path> \
      --gateway-websocket-broadcast-service-account-id <service_account_ID>
    ```

    Where:

    * `--name`: Trigger name.

    * `--batch-size`: Message batch size. This is an optional parameter. The values may range from 1 to 10. The default value is 1.
    * `--batch-cutoff`: Maximum wait time. This is an optional parameter. The values may range from 0 to 20 seconds. The default value is 10 seconds. The trigger groups messages for a period not exceeding `batch-cutoff` and sends them to WebSocket connections. The number of messages cannot exceed `batch-size`.

    * `--attachements-bucket`: Name of the bucket to save email attachments to. This is an optional setting.
    
    * `--attachements-service-account-id`: ID of the service account authorized to upload objects to an Object Storage bucket. This is an optional setting.

    * `--gateway-id`: API gateway ID.
    * `--gateway-websocket-broadcast-path`: Path in the OpenAPI specification. Messages will be sent through WebSocket connections established using this path.
    * `--gateway-websocket-broadcast-account-id`: Service account ID with permissions to send messages to WebSocket connections.

    Result:

    ```text
    id: a1sfe084v4h2********
    folder_id: b1g88tflruh2********
    created_at: "2023-08-04T08:45:31.131391Z"
    name: mail-trigger
    rule:
      mail:
        email: a1s8h8avglh2********-cho1****@serverless.yandexcloud.net
        batch_settings:
          size: "3"
          cutoff: 20s
        gateway_websocket_broadcast:
          gateway_id: d4eofc7n0mh2********
          path: /
          service_account_id: aje3932acdh2********
    status: ACTIVE
    ```

- API {#api}

  To create an email trigger, use the [create](../../triggers/api-ref/Trigger/create.md) REST API method for the [Trigger](../../triggers/api-ref/Trigger/index.md) resource or the [TriggerService/Create](../../triggers/api-ref/grpc/Trigger/create.md) gRPC API call.

{% endlist %}

Yandex API Gateway will automatically generate an email address for which the trigger will fire when messages are sent to it. To see it, [retrieve detailed trigger information](trigger-list.md#trigger-get).

## Checking the result {#check-result}

Check that the trigger operates correctly. Do it by viewing the [API gateway logs](../api-gw-logs.md) that present information about its incoming requests.

## Useful links {#see-also}

* [Email trigger that invokes a Cloud Functions function](../../../functions/operations/trigger/mail-trigger-create.md)
* [Email trigger that invokes a Serverless Containers container](../../../serverless-containers/operations/mail-trigger-create.md)