curl --request PATCH \
  --url https://api.sentvia.ai/v1/drafts/{id} \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "inbox_id": "<string>",
  "to": [
    "<string>"
  ],
  "subject": "<string>",
  "text": "<string>",
  "html": "<string>",
  "reply_to_message_id": "<string>",
  "scheduled_at": "<string>"
}
'

{
  "id": "<string>",
  "inbox_id": "<string>",
  "subject": "<string>",
  "status": "<string>",
  "scheduled_at": "<string>"
}