| Name | Type | Description | Notes |
|---|---|---|---|
| content | string | The base64-encoded contents of the file. | |
| type | string | The type of file being attached. | |
| filename | string | The name of the file being attached. | |
| disposition | string | Inline for content that can be displayed within the email, or attachment for any other files. | |
| content_id | string | An ID for the content. |