public static bool AppendFileOnServer(string fileName, Uri serverUri)
{
   // The URI described by serverUri should use the ftp:// scheme.
   // It contains the name of the file on the server.
   // Example: ftp://contoso.com/someFile.txt.
   // The fileName parameter identifies the file containing
   // the data to be appended to the file on the server.

   if (serverUri.Scheme != Uri.UriSchemeFtp)
   {
       return false;
   }
   // Get the object used to communicate with the server.
   FtpWebRequest request = (FtpWebRequest)WebRequest.Create(serverUri);
   request.Method = WebRequestMethods.Ftp.AppendFile;

   StreamReader sourceStream = new StreamReader(fileName);
   byte [] fileContents = Encoding.UTF8.GetBytes(sourceStream.ReadToEnd());
   sourceStream.Close();
   request.ContentLength = fileContents.Length;

   // This example assumes the FTP site uses anonymous logon.
   request.Credentials = new NetworkCredential
("anonymous","janeDoe@contoso.com");
   Stream requestStream = request.GetRequestStream();
   requestStream.Write(fileContents, 0, fileContents.Length);
   requestStream.Close();
   FtpWebResponse response = (FtpWebResponse) request.GetResponse();

   Console.WriteLine("Append status: {0}",response.StatusDescription);

   response.Close();
   return true;
}