@using (Html.BeginForm("Index", "Home", null, FormMethod.Post, new { enctype = "multipart/form-data" }))
{
    @Html.AntiForgeryToken()
    <div class="col-md-4">
        <div class="contact_form block">
            <div class="row">
                <div class="col-md-12 col-sm-12">
                    <div id="note"></div>
                </div>
            </div>
            <div id="fields">

                <div class="col-md-12 col-sm-6">
                    @Html.LabelFor(m => m.FromName)
                    @Html.TextBoxFor(m => m.FromName, new { @class = "form-control" })
                    @Html.ValidationMessageFor(m => m.FromName)
                </div>
                <div class="col-md-12 col-sm-6">
                    @Html.LabelFor(m => m.FromEmail)
                    @Html.TextBoxFor(m => m.FromEmail, new { @class = "form-control" })
                    @Html.ValidationMessageFor(m => m.FromEmail)
                </div>
                <div class="clear"></div>
                <div class="col-md-12 col-sm-6">
                    @Html.LabelFor(m => m.FromSubject)
                    @Html.TextBoxFor(m => m.FromSubject, new { @class = "form-control" })
                    @Html.ValidationMessageFor(m => m.FromSubject)
                </div>
                <div class="col-md-12">
                @using (Html.BeginForm("Multiple", "Home", FormMethod.Post, new { enctype = "multipart/form-data" }))
                {
                    <div id="multiple">
                        <input type="file" class="multiple" name="files" multiple />
                    </div>
                    <div id="single">
                        <input type="file" class="single" name="files" /><br />
                        <input type="file" class="single" name="files" /><br />
                        <input type="file" class="single" name="files" /><br />
                    </div>

                }
                </div>
                <div class="col-md-12">
                    @Html.LabelFor(m => m.Message)
                    @Html.TextAreaFor(m => m.Message, new { @class = "form-control" })
                    @Html.ValidationMessageFor(m => m.Message)
                </div>
                 <div class="col-md-12">
                     <div>
                         @if ((TempData["recaptcha"]) != null)
                         {
                            <p>@TempData["recaptcha"]</p>
                         }
                     </div>
                     <div class="g-recaptcha" data-sitekey="6LfVHx8TAAAAAMTDxxQrHDCxO1SyXf1GgbgNBZ5a"></div>
                 </div>

                <div class="col-md-12"><input class="shortcode_button" type="submit" value="Send"></div>

            </div>
        </div>
    </div>
}

public ActionResult Index()
{
    return View();
}

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<ActionResult> Index(EmailFormModel model)
{
    if (ModelState.IsValid)
    {
        string EncodedResponse = Request.Form["g-Recaptcha-Response"];
        bool IsCaptchaValid = (ReCaptcha.Validate(EncodedResponse) == "True" ? true : false);
        if(IsCaptchaValid)
        {

            var body = "<p>Email From: {0} ({1})</p><p>Message:</p><p>{2}</p>";
            var message = new MailMessage();
            message.To.Add(new MailAddress("***@gmail.com"));  // replace with valid value
            message.From = new MailAddress("***@ymailcom");  // replace with valid value
            message.Subject = "Your email subject";
            message.Body = string.Format(body, model.FromName, model.FromEmail, model.FromSubject, model.Message);
            message.IsBodyHtml = true;
            using (var smtp = new SmtpClient())
            {
                var credential = new NetworkCredential
                {
                    UserName = "***@gmail.com",  // replace with valid value
                    Password = "***"  // replace with valid value
                };
                smtp.Credentials = credential;
                smtp.Host = "smtp.gmail.com";
                smtp.Port = 587;
                smtp.EnableSsl = true;
                await smtp.SendMailAsync(message);
                //return RedirectToAction("Sent");
                ViewBag.Message = "Your message has been sent!";

                //TempData["message"] = "Message sent";
                ModelState.Clear();
                return View("Index");
            }

        }else
        {
            TempData["recaptcha"] = "Please verify that you are not a robot!";
        }
    }
    return View(model);
}

[HttpPost]
public ActionResult Multiple(IEnumerable<HttpPostedFileBase> files)
{
    foreach (var file in files)
    {
        if (file != null && file.ContentLength > 0)
        {
            file.SaveAs(Path.Combine(Server.MapPath("/uploads"), Guid.NewGuid() + Path.GetExtension(file.FileName)));
        }
    }
    return View();
}