//部分代码
//.h
#ifndef UnitSendEmailH
#define UnitSendEmailH
#include <NMsmtp.hpp>
#include <Psock.hpp>
//---------------------------------------------------------------------------
class TEmail:public TNMSMTP
{
private:
    AnsiString  SmtpType;
    AnsiString  SmtpUserId;
    AnsiString  SmtpFromAdr;
    AnsiString  SmtpFromName;
    AnsiString  SmtpToAdr;
    AnsiString  SmtpToCabCopy;
    AnsiString  SmtpAtt;
    AnsiString  SmtpLocalProgram;
    AnsiString  SmtpReplyTo;
    AnsiString  SmtpBodyText0;
    AnsiString  SmtpBodyText1;
    AnsiString  SmtpSubject;
    AnsiString  SmtpHost;
    USHORT SendedWStyle;
    void __fastcall IsSendFail(TObject *Sender);
    void __fastcall EmailServerConnect(TObject *Sender);
    void __fastcall IsSendSuccess(TObject *Sender);
public:
    bool __fastcall SendEmail(int WarnStyle);
    __fastcall TEmail(TComponent* Owner);
    __fastcall ~TEmail();
} ;
#endif


//.cpp
#pragma hdrstop

#include "UnitSendEmail.h"
#include <IniFiles.hpp>
#include <vcl.h>

//---------------------------------------------------------------------------

#pragma package(smart_init)
__fastcall TEmail::TEmail(TComponent* Owner):TNMSMTP(Owner)
{
    //读取发送电子邮电的设置参数
    TIniFile*FEmailParam=new TIniFile(ExtractFilePath(Application->ExeName)+"WGSendEmail.ini");

    //SmtpType=FEmailParam->ReadString("FROM", "SmtpType","");


    SmtpFromName=FEmailParam->ReadString("FROM", "SmtpFromName","");
    SmtpAtt=FEmailParam->ReadString("FROM", "SmtpAtt","");
    SmtpLocalProgram=FEmailParam->ReadString("FROM", "SmtpLocalProgram","");
    SmtpReplyTo=FEmailParam->ReadString("FROM", "SmtpReplyTo","");
    SmtpBodyText0=FEmailParam->ReadString("FROM", "SmtpBodyText0","");
    SmtpBodyText1=FEmailParam->ReadString("FROM", "SmtpBodyText1","");
    SmtpSubject=FEmailParam->ReadString("FROM", "SmtpSubject","");
    SmtpHost=FEmailParam->ReadString("FROM", "SmtpHost","");
    SmtpUserId=FEmailParam->ReadString("FROM", "SmtpUserId","");

    SmtpToAdr=FEmailParam->ReadString("TO", "SmtpToAdr","");
    SmtpToCabCopy=FEmailParam->ReadString("TO", "SmtpToCabCopy","");

    delete FEmailParam;

    OnConnect = EmailServerConnect;
    OnSuccess = IsSendSuccess;
    OnFailure = IsSendFail;


}
__fastcall TEmail::~TEmail()
{


}

bool __fastcall TEmail::SendEmail(int WarnStyle)
{
    WarnStyle = SendedWStyle;

    try
    {
        Host = SmtpHost;
        UserID = SmtpUserId;
        Connect();
        return 1;
    }
    catch(...)
    {
        return 0;
    }
}
void __fastcall TEmail::IsSendFail(TObject *Sender)
{
    Disconnect();
    SendEmail(SendedWStyle);
}
void __fastcall TEmail::IsSendSuccess(TObject *Sender)
{
    Disconnect();
}
void __fastcall TEmail::EmailServerConnect(TObject *Sender)
{

    try
    {
        //发送邮件
        SubType = mtPlain;//使用普通文本格式
        EncodeType = uuMime;//采用MIME编码
        PostMessage->FromAddress = SmtpUserId;
        PostMessage->FromName = SmtpFromName;
        PostMessage->ToAddress->Text = SmtpToAdr;
        PostMessage->ToCarbonCopy->Text = SmtpToCabCopy;
        PostMessage->Attachments->Text = SmtpAtt;
        PostMessage->Subject = SmtpSubject;
        PostMessage->LocalProgram = SmtpLocalProgram;
        PostMessage->ReplyTo = SmtpReplyTo;
        switch (SendedWStyle)
        {
          case 0: PostMessage->Body->Text = SmtpBodyText0;
          break;
          case 1: PostMessage->Body->Text = SmtpBodyText1;
          break;
        }
        SendMail();
    }
    catch(...)
    {
    }
}

void __fastcall TForm1::Button1Click(TObject *Sender)
{
NMSMTP1->Host = Edit1->Text;
NMSMTP1->UserID = Edit2->Text;
NMSMTP1->PostMessageA->ToAddress->Clear();
NMSMTP1->PostMessageA->ToAddress->Text = Edit3->Text;
NMSMTP1->PostMessageA->FromAddress = Edit3->Text;
NMSMTP1->PostMessageA->Subject = "Test message";
NMSMTP1->PostMessageA->Body->Add("this is a test message!");
NMSMTP1->PostMessageA->Body->Add("if this message is delivered, the Cancel button (Button2) wasn't pressed fast enough!");
NMSMTP1->Connect();

}
//---------------------------------------------------------------------------
void __fastcall TForm1::NMSMTP1Connect(TObject *Sender)
{
Memo1->Lines->Add("Connected,sending message!");

NMSMTP1->SendMail();
ShowMessage("发送成功!");
}
我是这样写的

执行到 
Memo1->Lines->Add("Connected,sending message!");
都没问题
NMSMTP1->SendMail();到这就出问题了
错误提示:you are not authorized to send mail as <Mail form:<dgyanyong@163.com>>,
authentication is required!
好像是没有权限的意思吧
用outlook发送邮件的时候需要密码,这个不需要吗?

我用outlook在本机上可以成功的发送邮件
host = smtp.163.com

自己机器上装个smtp服务器也可以

现在一般的服务器都需要验证。

执行sendmail前需要验证：
NMSMTP控件的验证：

在发送前写入：
if (CheckBox1->Checked)//如果需要验证
  {
     strUserName = Base64Encode(Edit4->Text);//将用户名编码
     strPassword=Base64Encode(Edit12->Text);//将密码编码

     NMSMTP1->Transaction("auth login");//开始验证
     NMSMTP1->Transaction(strUserName);
     NMSMTP1->Transaction(strPassword);
  }

可以去我的blog看一下
huzhangyou2002.mblogger.cn

有一个多线程发送email的例子