This method retracts a message from any recipients that have received the message. A message can be retracted whether or not the recipient has read the message, but the message will remain in that user’s account until it expires or the recipient deletes it. A session key must be submitted via the X-Session-Key header. The request body should be left empty. The message ID of the message you'd like to retract must be passed in the URL of this method. The response body will be empty. A successful transaction will receive a 200 status code.