const string docPath = @"***\TstDoc.doc";
Sender sndr = new Sender(Response, Server);
sndr.SendFileToClient(docPath, String.Format("application/{0}", "doc"), "testOutput.doc");

    public class Sender
    {
        private const string ContentDispositionTag = "content-disposition";
        private const string ContentDispositionFormat = "{0}; {1}={2}";
        private const string AttachmentTag = "attachment";
        private const string FileNameTag = "filename";

        private readonly HttpResponse response;
        private readonly HttpServerUtility server;

        public Sender(HttpResponse resp, HttpServerUtility srv)
        {
            response = resp;
            server = srv;
        }

        public void SendFileToClient(string fileName, string contentType, string nameForClient)
        {
            response.Buffer = true;
            response.Clear();
            response.ClearContent();
            response.ClearHeaders();
 
            response.ContentType = contentType;

            string tst = StrEncoder.GetEncodeFileName(nameForClient, server);
            response.AppendHeader(
                  ContentDispositionTag,
                  String.Format(
                      ContentDispositionFormat,
                      AttachmentTag,
                      FileNameTag,
                      tst
                      )
                  );
            response.WriteFile(fileName);
            response.Flush();
            response.End();
        }
    }