TemplateMessage

Field	Type	Required	Description
`title`	`string`	yes	max length 255
`body`	`string`	yes
`image`	`string	null`
`imageType`	`string`		one of: `custom`, `externalUrl`, `product`

Example

{
  "title": "TheTitle",
  "body": "BodyBodyBody",
  "image": "http://url",
  "imageType": "custom"
}