Pass true to post the message as the authed user, instead of as a bot. Defaults to false. See [chat.postMessage](chat.postMessage#authorship).

A JSON-based array of structured attachments, presented as a URL-encoded string.

A JSON-based array of structured blocks, presented as a URL-encoded string.

Channel, private group, or DM channel to send message to. Can be an encoded ID, or a name. See [below](#channels) for more details.

Find and link channel names and usernames.

Change how messages are treated. Defaults to `none`. See [chat.postMessage](chat.postMessage#formatting).

Unix EPOCH timestamp of time in future to send the message.

Used in conjunction with `thread_ts` and indicates whether reply should be made visible to everyone in the channel or conversation. Defaults to `false`.

How this field works and whether it is required depends on other fields you use in your API call. [See below](#text_usage) for more detail.

Provide another message's `ts` value to make this message a reply. Avoid using a reply's `ts` value; use its parent instead.

Pass true to enable unfurling of primarily text-based content.

Pass false to disable unfurling of media content.