By default, messages sent via the Server API are not moderated. When you enable Moderate messages sent by server API, these messages will be passed through your configured sensitive word filters, content moderation rules, and any filtering logic you have set up in the pre-messaging webhook service.
You can enable this feature on the Security & Moderation page in the Console. Just turn on Moderate messages sent by server API.
If you have any questions about this feature, feel free to create a ticket to us.