public class HomeController : Controller
{
    public ActionResult Index()
    {
        return View();
    }

    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<ActionResult> Index(EmailFormModel model, IEnumerable<HttpPostedFileBase> files)
    {
        if (ModelState.IsValid)
        {

            List<string> paths = new List<string>();

            foreach (var file in files)
            {

                if (file.ContentLength > 0)
                {
                    var fileName = Path.GetFileName(file.FileName);
                    var path = Path.Combine(Server.MapPath("~/uploads"), fileName);
                    file.SaveAs(path);
                    paths.Add(path);
                }
            }

                var message = new MailMessage();
                foreach (var path in paths)
                {
                    var fileInfo = new FileInfo(path);
                    var memoryStream = new MemoryStream();
                    using (var stream = fileInfo.OpenRead())
                    {
                        stream.CopyTo(memoryStream);
                    }
                    memoryStream.Position = 0;
                    string fileName = fileInfo.Name;
                    message.Attachments.Add(new Attachment(memoryStream, fileName));
                }

                //Rest of business logic here
                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>Subject: {2} </p><p>Message:</p><p>{3}</p>";
                    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);
                        ViewBag.Message = "Your message has been sent!";

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


        }

        public ActionResult Upload()
        {
            var file = Request.Files["Filedata"];
            string savePath = Server.MapPath(("~/uploads") + file.FileName);
            file.SaveAs(savePath);

            return Content(Url.Content(("~/uploads") + file.FileName));
        }

<script type="text/javascript" src="@Url.Content("~/Scripts/jquery-1.10.2.min.js")"></script>
<script type="text/javascript" src="@Url.Content("~/Content/UploadifyContent/jquery.uploadify.js")"></script>
<script type="text/javascript" src="@Url.Content("~/Content/UploadifyContent/jquery.uploadify.min.js")"></script>
<link rel="stylesheet" type="text/css" href="@Url.Content("~/Content/UploadifyContent/uploadify.css")" />

<script type="text/javascript">
    $(function () {
        $('#file_upload').uploadify({
            'swf': "@Url.Content("~/Content/UploadifyContent/uploadify.swf")",
            'cancelImg': "@Url.Content("~/Content/UploadifyContent/uploadify-cancel.png")",
            'uploader': "@Url.Action("Upload", "Home")",
            'onUploadSuccess': function (file, data, response) {
                $("#uploaded").append("<img src='" + data + "' alt='Uploaded Image' />");
            }
        });
    });
</script>

@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, null, new { @class = "text-danger" })
                </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, null, new { @class = "text-danger" })
                </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, null, new { @class = "text-danger" })
                </div>
                <div class="col-md-12 col-sm-6">
                    <form action="" method="post" enctype="multipart/form-data">
                        <label for="file1">Attachments</label>
                        <input type="file" name="files" id="file1" multiple />
                    </form>
                    <div id="uploaded"></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, null, new { @class = "text-danger" })
                </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>
}