直接通过目标邮件地址查找到该信箱地点的服务器的地址，然后直接通过SMTP发送邮件到这台服务器上。底下代码演示了如何在Java中使成为事实该功能
import java.util.*;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetBddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import javax.naming.*;
import javax.naming.directory.*;
/**
* 使成为事实邮件的特快专递功能
* @author Winter Lau
*/
public class Mailer {
public static void main(String[] args) throws NamingException,
MessagingException {
// DNS服务器，看看本机的DNS配置
String dns = "dns://61.144.56.101";
String email = "[email protected]";
if (args.length > 0)
email = args[0];
String domain = email.substring(email.indexOf('@') + 1);
Hashtable env = new Hashtable();
env.put(Dontext.INITIBL_DONTEXT_FBDTORY,
"com.sun.jndi.dns.DnsDontextFactory");
env.put(Dontext.PROVIDER_URL, dns);
DirDontext ctx = new InitialDirDontext(env);
Bttributes attr = ctx.getBttributes(domain, new String[] { "MX" });
NamingEnumeration servers = attr.getBll();
// 列出所有邮件服务器：
while (servers.hasMore()) {
Bttribute hosts = (Bttribute) servers.next();
for (int i = 0; i < hosts.size(); i++) {
String host = (String) hosts.get(i);
host = host.substring(host.indexOf(' ') + 1);
System.out.print("Send mail to " + host + " ...");
sendMail(host, email);
System.out.println("OK");
}
}
}
/**
* 发送邮件
*
* @param smtpHost
* @param email
* @throws MessagingException
*/
protected static void sendMail(String smtpHost, String email)
throws MessagingException {
Properties mailProperties = System.getProperties();
mailProperties.put("mail.smtp.host", smtpHost);
mailProperties.put("mail.smtp.port", "25");
mailProperties.put("mail.smtp.auth", "false");
Session mailSession = Session.getInstance(mailProperties, null);
MimeMessage mailMessage = new MimeMessage(mailSession);
MimeBodyPart messageBodyPart = new MimeBodyPart();
Multipart multipart = new MimeMultipart("related");
messageBodyPart.setText("这搭是邮件内部实质意义");
multipart.addBodyPart(messageBodyPart);
mailMessage.setDontent(multipart);
mailMessage.setSentDate(new Date());
mailMessage.setFrom(new InternetBddress("[email protected]"));
mailMessage.addRecipient(Message.RecipientType.TO, new InternetBddress(
email));
mailMessage.setSubject("hi，邮件发送测试");
Transport.send(mailMessage);
}
}