最后，经过大量的尝试和试验，这段代码对我有用.很遗憾，经过与 Zoho 团队的大量跟进和通话，我好几天都没有得到他们的任何帮助.

Finally, after a lot of hits and trials, this code worked for me. It's bad that after a lot of follow-up and calls with the Zoho team, I did not receive any help from them for many days.

[HttpPost]
public ActionResult Callback()
{
    string rawBody = GetDocumentContents(Request);
    dynamic eventObj = JsonConvert.DeserializeObject(rawBody);
    using (var context = new ZohoApiTestEntities())
    {
        var rowDetails = new tblWebhook();
        rowDetails.PhoneNo = "*********";
        //eventObj comes in JSOn format with two keys, "requests" and "notifications" each containing a JSON object https://www.zoho.com/sign/api/#webhook-management
        //you can get your required details like this
        string recipientName = eventObj.notifications.performed_by_name.ToString();
        rowDetails.Notes1 = recipientName;
        context.tblWebhooks.Add(rowDetails);
        context.SaveChanges();
    }
    return new HttpStatusCodeResult(HttpStatusCode.OK);
}

private string GetDocumentContents(HttpRequestBase Request)
{
    string documentContents;
    using (Stream receiveStream = Request.InputStream)
    {
        using (StreamReader readStream = new StreamReader(receiveStream, Encoding.UTF8))
        {
            documentContents = readStream.ReadToEnd();
        }
    }
    return documentContents;
}