We try to send by API https://desk.zoho.com/api/v1/tickets/{ticket_id}/sendReply but it tells us 

"{

    "errorCode": "INTERNAL_SERVER_ERROR",

    "message": "An internal server error occurred while performing this operation."

}

.

In the header are the values of  orgId and  Authorization  and in the body by raw (json) the list of parameters like :

{

  "channel" : "MAIL",

  "to" : "algo @correo.cl",

  "fromEmailAddress" : " soporte@otrocorreo.cl",

  "contentType" : "plainText",

  "content" : "We have identified the root cause and fixed it.",

  "isForward" : "true"

}