public void Test163()
        {
            var imapServer = "imap.163.com";
            var port = 993;
            using (ImapClient client = new ImapClient(imapServer, port, "xxxx@163.com", "pwd", AuthMethod.Login, true))
            {
                // Returns a collection of identifiers of all mails matching the specified search criteria.
                IEnumerable<uint> uids = client.Search(SearchCondition.Unseen());
                // Download mail messages from the default mailbox.
                IEnumerable<MailMessage> messages = client.GetMessages(uids,FetchOptions.HtmlOnly);

                Console.WriteLine("We are connected!");
            }

        }