Unable to Send Ticket Reply as a Contact in Zoho Desk?

Unable to Send Ticket Reply as a Contact in Zoho Desk?

Hi Zoho Desk Team,

I am trying to send a reply to a ticket on behalf of a contact using the Zoho Desk API. My goal is to have the contact's response reflected in the ticket conversation, but I am facing an issue where only the ticket author can comment.

Here’s the API request I am using:

Endpoint:
POST https://desk.zoho.com/api/v1/tickets/{ticketId}/sendReply

Request Body:

{
  "channel": "EMAIL",
  "to": "support@my.zohodesk.com",
  "fromEmailAddress": "sample@email.com",
  "contentType": "plainText",
  "content": "sample comment.",
  "isForward": "true"
}

Error Response:

{
    "errorCode": "UNPROCESSABLE_ENTITY",
    "message": "The value passed for the 'fromEmailAddress' parameter is invalid."
}

I want to send replies/comments as a specific contact in Zoho Desk, but it seems only the ticket author is allowed to comment. How can I achieve this? Is there a way to post a comment or reply as a contact associated with the ticket?

Any guidance would be appreciated.

Thanks!