javamail问题！？？？

[passwords]

请问在用java中写发送邮件的程序中使用SMTP服务器的地址怎么设定？有什么规则吗？

[gdsean]

public static boolean sendmail(String from, String[] emailto, String subject, String message, String smtp)
{
try
{
Properties props = new Properties();
//设置smtp服务器
props.put("mail.smtp.host", smtp);
// create some properties and get the default Session
javax.mail.Session session1 = javax.mail.Session.getDefaultInstance(props, null);
session1.setDebug(false);
// create a message
Message msg = new MimeMessage(session1);
// set the from and to address
InternetAddress addressFrom = new InternetAddress(from);
msg.setFrom(addressFrom);

InternetAddress[] addressTo = new InternetAddress[emailto.length];
for (int i = 0; i < emailto.length; i++){
addressTo[i] = new InternetAddress(emailto[i]);
}
msg.setRecipients(Message.RecipientType.TO, addressTo);

// Setting the Subject and Content Type
msg.setSubject(subject);
msg.setContent(message, "text/html");
Transport.send(msg);
}catch(Exception e)
{
return false;
}
return true;
}

[xchfriend]

package mail;
import java.util.*;
import javax.mail.*;
import java.io.*;
import javax.mail.internet.*;
import javax.activation.*;

public class Email
{
public Email()
{
}

public void sendmail(String to,String subject,String body,String filename)
{
Session session;
MimeMessage message;
String host="smtp.citiz.net";
String from="[e-mail]";
Properties props=System.getProperties();
props.put("mail.smtp.host",host);
session=Session.getInstance(props,null);
message=new MimeMessage(session);

try
{
message.setFrom(new InternetAddress(from));
message.addRecipient(Message.RecipientType.TO,new InternetAddress(to));
message.setSubject(subject);
MimeBodyPart mbp1=new MimeBodyPart();
mbp1.setText(body);
MimeBodyPart mbp2=new MimeBodyPart();
FileDataSource fds=new FileDataSource(filename);
mbp2.setDataHandler(new DataHandler(fds));
mbp2.setFileName(filename);
Multipart mp=new MimeMultipart();
mp.addBodyPart(mbp1);
mp.addBodyPart(mbp2);
message.setContent(mp);
message.setSendDate(new java.util.Date());
Transport transport=session.getTransport("smtp");
transport.connect("smtp.citiz.net","xchfriend","64322075");
transport.send(message);
}

catch(MessagingException e){}
}
}