记得原来有人问过用socket实现smtp,这是我的一部分代码

namespace mySmtp
{
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Collections;
    interface ITransport
    {
        void setHost(String smtpHost);
        String getHost();
    
        void setPort(int smtpPort);
        int getPort();
    
        void sendMail(MailMessage msg);
    }
    public class Smtp : ITransport
    {
        private String smtpHost;
        private int smtpPort;
        
        public Smtp()
        {
       //smtpHost = "127.0.0.1";
       //smtpPort = 25;
        }
        
        public Smtp(String host, int port)
        {
       smtpHost = host;
       smtpPort = port;