I always use this to get the file size of a file before downloading it:

                        ' FTP setup
                        loFtpWebRequest = System.Net.FtpWebRequest.Create(New Uri(lcURI))
                        loFtpWebRequest.Credentials = New System.Net.NetworkCredential(cUsername, cPassword)
                        loFtpWebRequest.Method = System.Net.WebRequestMethods.Ftp.GetFileSize
                        loFtpWebRequest.UseBinary = True
                        loFtpWebRequest.UsePassive = True
                        loFtpWebRequest.KeepAlive = False
                        loFtpWebRequest.Timeout = 10000000
                        loFtpWebRequest.ReadWriteTimeout = 10000000

                        Using loFtpWebResponse As System.Net.FtpWebResponse = loFtpWebRequest.GetResponse()

                            ' Get the length
                            lnContentLength = loFtpWebResponse.ContentLength

                            ' Assign the the public property
                            nSize = lnContentLength

                        End Using

However, on one specific server, this does not work. The Using line cannot be executed and it seems they do not allow us to get the file size of the file.

Anyone knows if this is possible for a FTP server to restrict that? Also, a workaround would be appreciated.