FileAttachment.js

$('#FileSend').click(function() {
            var files = document.getElementById('FileUpload').files;
            var AttachmentData =new FormData();
            for (var i = 0; i < files.length; i++) {
                AttachmentData.append(files[i].name, files[i]);
            }
            AttachmentData.append('EmailTo', document.getElementById('txtSendTo').value);
            AttachmentData.append('EmailCC', document.getElementById('txtSendCC').value);
            AttachmentData.append('EmailBCC', document.getElementById('txtSendBCC').value);
            AttachmentData.append('EmailSubject', document.getElementById('txtSubject').value);
            AttachmentData.append('EmailMessage', document.getElementById('txtMessage').value);

            $.ajax({
                url: '/Home/SendEmail',
                type: "POST",
                contentType: false, // Not to set any content header
                processData: false, // Not to process data
                data: AttachmentData,
                success: function (result) {
                    alert(result);
                },
                error: function (err) {
                    alert(err);
                }
            });
    });