jmail 发送的邮件 如何换行？ 小弟我的源代码如下，发送邮件已经没有关问题，但是收到的邮件内容和小弟我在页面输入后传过来的不一样，输入使用了回车键换了行，可是收到的邮件没换行。为什么？请高手指教！

jmail 发送的邮件 怎么换行？ 我的源代码如下，发送邮件已经没问题，但是收到的邮件内容和我在页面输入后传过来的不一样，输入使用了回车键换了行，可是收到的邮件没换行。为什么？？？请高手指教！！！
public   boolean   sendMail(String   ttitle,String   tcontent,String[]   ttos,String[]   attachFile){

Properties   props   =   new   Properties();
props.put( "mail.smtp.host ",   "xx.xx.cn ");
props.put( "mail.smtp.auth ",   "true ");
Session   s   =   Session.getInstance(props);
s.setDebug(true);
MimeMessage   message   =   new   MimeMessage(s);
try   {
InternetAddress   from   =   new   InternetAddress( "amyfe@163.com.cn ");
message.setFrom(from);
InternetAddress[]       address       =       new   InternetAddress[ttos.length];
for(int   i=0;i <address.length;i++){
address[i]   =   new   InternetAddress(ttos[i]);
}
message.setRecipients(Message.RecipientType.TO,address);
message.setSubject(ttitle);
message.setSentDate(new   Date());
Multipart   mm   =   new   MimeMultipart();
//   给消息对象设置内容
BodyPart   mdp   =   new   MimeBodyPart();
System.out.println( "tcontent:     "+tcontent);
mdp.setContent(tcontent,   "text/html;charset=gb2312 ");
mm.addBodyPart(mdp);
//附件相关
//String[]   attachFile   =   { "C:\\MSINET.OCX ", "C:\\RICHTX32.OCX "};
if(attachFile!=null&&attachFile.length> 0){
FileDataSource   fds   =   null;
BodyPart   attachbodypart   =   null;
for(int   i=0;i <attachFile.length&&!attachFile[i].equals( " ");i++){
attachbodypart   =   new   MimeBodyPart();
fds   =new   FileDataSource(attachFile[i]);  
attachbodypart.setDataHandler(new   DataHandler(fds));   //设置数据源  
attachbodypart.setFileName(MimeUtility.encodeWord(fds.getName(), "UTF-8 ", "Q "));
//new   String(fds.getName().getBytes( "gb2312 "), "iso8859 ")
mm.addBodyPart(attachbodypart);
}
message.setContent(mm);
message.saveChanges();
}
Transport   transport   =   s.getTransport( "smtp ");
transport.connect( "xx.xx.cn ",   "amyfe ",   "123456 ");
transport.sendMessage(message,   message.getAllRecipients());
transport.close();
System.out.println( "发送成功! ");
return   true;
}   catch   (Exception   e)   {
e.printStackTrace();
return   false;
}

}

------解决方案--------------------------------------------------------
在发出之前用replaceAll()方法把\n换成<br>