private void btnsend_Click(object sender, System.EventArgs e)

{

// 将鼠标形状改为漏斗状http://www.shengfang.org

Cursor cr = Cursor.Current;

Cursor.Current = Cursors.WaitCursor;http://www.shengfang.org

//定义变量http://www.shengfang.org

string Data;

byte[] szData;

string CRLF = "\r\n";

//创建与服务器25端口的连接http://www.shengfang.org

TcpClient SmtpServ = new TcpClient(txtsmtp.Text,25);

lstlog.Items.Clear();

//显示服务器初始信息http://www.shengfang.org

NetworkStream NetStrm = SmtpServ.GetStream();

StreamReader RdStrm= new StreamReader(SmtpServ.GetStream());

lstlog.Items.Add(RdStrm.ReadLine());

//标志发件人http://www.shengfang.org

Data = "HELO server " + CRLF;

szData = System.Text.Encoding.ASCII.GetBytes(Data.ToCharArray());

NetStrm.Write(szData,0,szData.Length);

lstlog.Items.Add(RdStrm.ReadLine());

//标志http://www.shengfang.org发件人

Data = "MAIL FROM: " + "<" + txtfrom.Text + ">" + CRLF;

szData = System.Text.Encoding.ASCII.GetBytes(Data.ToCharArray());

NetStrm.Write(szData,0,szData.Length);

lstlog.Items.Add(RdStrm.ReadLine(

// 标志http://www.shengfang.org收件人

Data = "RCPT TO: " + "<" + txtto.Text + ">" + CRLF;

szData = System.Text.Encoding.ASCII.GetBytes(Data.ToCharArray());

NetStrm.Write(szData,0,szData.Length);

lstlog.Items.Add(RdStrm.ReadLine());

//准备http://www.shengfang.org发送内容

Data = "DATA " + CRLF;

szData = System.Text.Encoding.ASCII.GetBytes(Data.ToCharArray());

NetStrm.Write(szData,0,szData.Length);

lstlog.Items.Add(RdStrm.ReadLine());

//发送http://www.shengfang.org主题

Data = "SUBJECT: " + http://www.shengfang.org txtsub.Text + CRLF ;

//发送内容

Data = Data+ txtmsg.Text + CRLF ;

//结束发送

Data = Data+ "." + CRLF;

szData =http://www.shengfang.org System.Text.Encoding.ASCII.GetBytes(Data.ToCharArray());

NetStrm.Write(szData,0,szData.Length);

lstlog.Items.Add(RdStrm.ReadLine());

//退出

Data = "QUIT " + CRLF;

szData =http://www.shengfang.org System.Text.Encoding.ASCII.GetBytes(Data.ToCharArray());

NetStrm.Write(szData,0,szData.Length);

lstlog.Items.Add(RdStrm.ReadLine());

//关闭连接

NetStrm.Close();http://www.shengfang.org

RdStrm.Close();

lstlog.Items.Add("连接关闭");

lstlog.Items.Add("发送成功");

//将鼠标恢复箭头状

Cursor.Current = cr;

}http://www.shengfang.org