具体的实现SMTP协议的程序正是通过它一步一步实现并最终实现发送简单邮件甚至带附件的邮件的功能。而它的实现是调用以上给出的各个函数的结果。以下就简单的通过几个SMTP命令的格式来实现。

private bool SendEmail()

{

//连接网络

try

{

//建立一个TCP连接

tc=new TcpClient(mailserver, mailserverport);

}

catch

{

MessageBox.Show ("连接失败","请确认");

return false;

}

//获取当前流的资料

ns = tc.GetStream();

SMTPCodeAdd();

//验证网络连接是否正确

if(RightCodeHT[RecvResponse().Substring(0,3)]==null)

{

return false;

}

string[] SendBuffer;

string SendBufferstr;

//进行SMTP验证

if(ESmtp)

{

SendBuffer=new String[4];

SendBuffer[0]="EHLO " + mailserver + enter;

SendBuffer[1]="AUTH LOGIN" + enter;

       //核对用户名和密码

SendBuffer[2]=Base64Encode(username) + enter;

SendBuffer[3]=Base64Encode(password) + enter;

if(!Dialog(SendBuffer,"SMTP服务器验证失败，请核对用户名和密码"))

return false;

}

else

{   SendBufferstr="HELO " + mailserver + enter;

       if(!Dialog(SendBufferstr,""))

       return false;

}

   //核对发件人地址

SendBufferstr="MAIL FROM:<" + From + ">" + enter;

if(!Dialog(SendBufferstr,"发件人地址错误，或不能为空"))

return false;

//把传过来的收件人的地址分割然后提交给服务器

string split=";";

string []address=Regex.Split (Recipient,split);

SendBuffer=new string [address.Length];

for(int i=0;i<SendBuffer.Length;i++)

{

SendBuffer[i]="RCPT TO:<" +address[i]+">" + enter;

}

if(!Dialog(SendBuffer,"收件人地址有误"))

return false;

    //发送相关的邮件正文

SendBufferstr="DATA" + enter;

if(!Dialog(SendBufferstr,""))

return false;

    //提示发件人信息

SendBufferstr="From:" + FromName + "<" + From +">" +enter;

SendBufferstr += enter + "." + enter;

if(!Dialog(SendBufferstr,"错误信件信息"))

return false;

   //断开连接

SendBufferstr="QUIT" + enter;

if(!Dialog(SendBufferstr,"断开连接时错误"))

return false;

ns.Close();

    tc.Close();

FilePath=null;

return true;

}