protected void btnDownload_Click(object sender, EventArgs e)
    {
        Stream outputStream = ExecuteMerge("all", DocumentFormat.Rtf);

        outputStream.Seek(0, SeekOrigin.Begin);
        StreamCopyHelper.Copy(outputStream, Response.OutputStream);

        Response.StatusCode  = (int)HttpStatusCode.OK;
        Response.ContentType = "application/rtf";
        Response.AddHeader("Content-Disposition", "attachment; filename=RichEditMailMerge.rtf");
        Response.End();
    }
    private void RefreshPreview(string previewName)
    {
        Response.StatusCode  = (int)HttpStatusCode.OK;
        Response.ContentType = "text/html";

        Stream outputStream = ExecuteMerge(previewName, DocumentFormat.Html);

        outputStream.Seek(0, SeekOrigin.Begin);
        StreamCopyHelper.Copy(outputStream, Response.OutputStream);

        Response.End();
    }