public class ContactController : SurfaceController 
{
    [HttpPost]
    public JsonResult SendMail(Contact model)
    {
        if (ModelState.IsValid)
        {
            var sb = new StringBuilder();
            sb.AppendFormat("<p>Name:{0}</p>", model.YourName);
            sb.AppendFormat("<p>Email:{0}</p>", model.Email);

            sb.AppendFormat("<p>Message:{0}</p>", model.Message);

            library.SendMail(model.Email, "[email protected]", model.Subject,                sb.ToString(), true);
            return Json(true);

        }
        return Json(false);
    }
}

I have this surface controller and it is doing exactly what I want BUT my problem is two fold:

1. All of a sudden when I click submit on my form it will not post to the controller instead the browser is throwing a JS error > Uncaught ReferenceError: Sys is not defined

This is the form

@using (Ajax.BeginForm("SendMail", "Contact", new AjaxOptions
{
   HttpMethod = "POST",
   OnFailure = "ShowError()",
   OnSuccess = "ShowSuccess()"
}))
{

@Html.ValidationMessageFor(model => model.YourName)
@Html.ValidationMessageFor(model => model.Email)
@Html.ValidationMessageFor(model => model.Subject)
@Html.ValidationMessageFor(model => model.Message)



@Html.ValidationSummary(true, "Errors")

@Html.EditorFor(model => model.YourName)


@Html.EditorFor(model => model.Email)


@Html.EditorFor(model => model.Subject)


@Html.TextAreaFor(model => model.Message)

<input type="submit" id="submit-mail" class="submit-btn rounded" value="SEND MESSAGE" />

Uncaught ReferenceError: Sys is not defined

2.How can I process the result of the controller, as you can see I am trying to use JSON but all that happens (when it was working and posting to the controller) the browser just shows the string True/False instead of running the js functions.

Any Ideas?