Create Ticket External Messages

curl --request POST \
  --url https://public.api.serval.com/v2/tickets/{ticket_id}/external-messages \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "channelTarget": {
    "email": {}
  },
  "messages": [
    {
      "messageId": "<string>",
      "externalMessageId": "<string>",
      "externalMessageData": {}
    }
  ]
}
'

{
  "data": [
    {
      "id": "<string>",
      "externalMessageId": "<string>",
      "messageId": "<string>",
      "sourceId": "<string>",
      "isOrigin": true,
      "createdAt": "2023-11-07T05:31:56Z",
      "updatedAt": "2023-11-07T05:31:56Z",
      "toRecipientEmails": [
        "<string>"
      ],
      "ccRecipientEmails": [
        "<string>"
      ]
    }
  ]
}