为什么发html的邮件收不到？

有两个，第一个是怎么也不好用，第二个（书上的例子）好用，但两个代码基本上是一样的，我怎么看也看不出错在哪里，如果你看出来了，请告诉我，请不要乱贴代码，我只想知道原因。
第一个：
<%@ page import="java.util.*,javax.activation.*, javax.mail.*, javax.mail.internet.*" %>
<%
try
{
Properties props =System.getProperties();
props.put("mail.smtp.host", "xxx");
props.put("mail.smtp.auth","true");
Session s = Session.getInstance(props,null);
MimeMessage message=new MimeMessage(s);
InternetAddress from=new InternetAddress("xxx@sohu.com");
message.setFrom(from);
String to=request.getParameter("to");
message.setRecipient(Message.RecipientType.TO,new InternetAddress(to));
String subject=request.getParameter("subject"),text=request.getParameter("text");
message.setSubject(subject);
message.setSentDate(new Date());
BodyPart mbp=new MimeBodyPart();
MimeMultipart mm=new MimeMultipart();
//String type=request.getParameter("type");
String type="text/html;charset=gb2312";
mbp.setContent(text,type);
mm.addBodyPart(mbp);
message.setContent(mm);
message.saveChanges();
Transport trans=s.getTransport("smtp");
trans.connect("xxx","用户名","密码");
trans.sendMessage(message,message.getAllRecipients());
trans.close();
}
catch(Exception e)
{
out.print(e.toString());
}
%>

<html>
<p align="center">Mail has been sent. Check your Inbox.</p>
<p align="center"><a href="inputMail.jsp">Click here to send
another!</a></p>
</html>


第二个：
<HTML><HEAD><TITLE>网络发件箱</TITLE>
<%@ page import=" javax.mail.*,java.util.*,javax.activation.*,javax.mail.internet.*"
contentType="text/html;charset=GB2312"%>
</head><body>
<%
String host = request.getParameter("host");
try{
Properties props = System.getProperties();
Session mailSession = Session.getInstance(props, null);
props.put("mail.smtp.host", host);
props.put("mail.smtp.auth", "true");
mailSession.setDebug(true);
Message message = new MimeMessage(mailSession);
message.setFrom(new InternetAddress(request.getParameter("sender")));
message.addRecipient(Message.RecipientType.TO,
new InternetAddress(request.getParameter("receiver")));
message.setSubject("你好啊");
message.setContent(multipart);
message.saveChanges();
Transport transport = mailSession.getTransport("smtp");
transport.connect(host, request.getParameter("username"), request.getParameter("password"));
transport.sendMessage(message, message.getAllRecipients());
transport.close();
%>
<P>你的邮件已经成功发送！</P>
<%
}
catch(MessagingException m){
out.println(m.toString());
}
%>

</BODY></HTML>