public static bool AcceptAllCertificatePolicy(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
{
    return true;
}

public static string Upload_SSL(string filenameSrc)
{

    ServicePointManager.ServerCertificateValidationCallback = AcceptAllCertificatePolicy;

    FileInfo fileInfSrc = new FileInfo(filenameSrc);
    FtpWebRequest reqFTP;

    // Create FtpWebRequest object from the Uri provided
    if (strDirectory.Trim() != "")
    {
        reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + strHost.Trim() + "/" + strDirectory.Trim() + "/" + fileInfSrc.Name.Trim()));
    }
    else
    {
        reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + strHost.Trim() + "/" + fileInfSrc.Name.Trim()));
    }

    // Provide the WebPermission Credintials
    reqFTP.Credentials = new NetworkCredential(strUser.Trim(), strPass.Trim());

    reqFTP.EnableSsl = true;

    // Test Fabio du 15/01/2013
    reqFTP.Proxy = null;

    // By default KeepAlive is true, where the control connection is not closed
    // after a command is executed.
    reqFTP.KeepAlive = false;

    // Specify the command to be executed.
    reqFTP.Method = WebRequestMethods.Ftp.UploadFile;

    // Specify the data transfer type.
    reqFTP.UseBinary = true;

    // Notify the server about the size of the uploaded file
    reqFTP.ContentLength = fileInfSrc.Length;

    // The buffer size is set to 8kb
    int buffLength = 8192;
    byte[] buff = new byte[buffLength];
    int contentLen;

    // Opens a file stream (System.IO.FileStream) to read the file to be uploaded
    FileStream fs = fileInfSrc.OpenRead();

    try
    {
        // Stream to which the file to be upload is written
        Stream strm = reqFTP.GetRequestStream();

        // Read from the file stream 2kb at a time
        contentLen = fs.Read(buff, 0, buffLength);


        // Till Stream content ends
        while (contentLen != 0)
        {
            // Write Content from the file stream to the FTP Upload Stream
            strm.Write(buff, 0, contentLen);
            contentLen = fs.Read(buff, 0, buffLength);
        }

        // Close the file stream and the Request Stream
        strm.Close();
        fs.Close();
    }
    catch (Exception ex)
    {
        fs.Close();
        return (ex.Message);
    }

    return "ok";
}

myFtp.Class1.strHost = "ftp://XXXXXXXXXXXXX";
myFtp.Class1.strPass = "*****************";
myFtp.Class1.strUser = "*********";
myFtp.Class1.nPort = 21;
myFtp.Class1.Upload_SSL(@"D:Test.txt");