电子邮件那点事儿

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> -->package org.hvp.test;

import java.util.Hashtable;

import javax.naming.NamingException;
import javax.naming.directory.Attributes;
import javax.naming.directory.DirContext;
import javax.naming.directory.InitialDirContext;

/**
 * @author "惠万鹏"
 *
 */
public class Smtp
{
    public static String getSmtpServer(String dns, String domain)
            throws NamingException
    {
        /** 如果domain传入的是一个email */
        if (domain.indexOf("@") > 0)
        {
            domain = domain.substring(domain.indexOf("@") + 1);
        }
        Hashtable<String, String> properties = new Hashtable<String, String>();
        properties.put("java.naming.factory.initial","com.sun.jndi.dns.DnsContextFactory");
        properties.put("java.naming.provider.url", "dns://" + dns);
        DirContext ctx = new InitialDirContext(properties);
        Attributes attributes = ctx.getAttributes(domain, new String[] { "MX" });
        String recordMx = (String) attributes.get("MX").get();
        if (recordMx != null)
        {
            recordMx = recordMx.substring(recordMx.indexOf(" ") + 1);
        }
        System.out.println("-------->" + recordMx + "<-------");
        return recordMx;
    }
    
    
    
    public static void main(String[] args) throws NamingException
    {
        Smtp.getSmtpServer("10.1.3.210", "[e-mail]"); 
    }
}

<!--<br /> <br /> Code highlighting produced by Actipro CodeHighlighter (freeware)<br /> http://www.CodeHighlighter.com/<br /> <br /> -->package org.hvp.test;

import java.net.*;
import java.io.*;

public class Test {

    private static String END_FLAG = "\r\n";

    public static void main(String[] args) throws Exception {
        String mx = "163mx00.mxmail.netease.com";
        InetAddress addr = InetAddress.getByName(mx);
        Socket socket = new Socket(addr, 25);

        InputStream in = socket.getInputStream();
        OutputStream out = socket.getOutputStream();

        // 连接成功后服务器会响应：
        response(in);

        // 首先发送HELO命令：
        send("HELO www.javasprite.com" + END_FLAG, out);
        response(in);

        // 然后发送发件人地址：
        send("MAIL FROM: [e-mail]" + END_FLAG, out);
        response(in);

        // 设置收件人地址：
        send("RCPT TO: [e-mail]" + END_FLAG, out);
        response(in);

        // 开始发送邮件正文：
        send("DATA" + END_FLAG, out);
        response(in);

        send("From: [e-mail]" + END_FLAG, out);
        send("To: [e-mail]" + END_FLAG, out);
        send("Subject: Test without smtp server" + END_FLAG, out);
        send("Content-Type: text/plain;" + END_FLAG, out);
        send(END_FLAG + END_FLAG, out);

        // 发送邮件正文，如果用中文，需要BASE64编码：
        send("text message body!" + END_FLAG, out);
        // 每行以\r\n结束，不可过长，可拆成多行。

        // 以"\r\n.\r\n"作为结束标志：
        send(END_FLAG + "." + END_FLAG, out);
        response(in);

        // 结束并确认发送：
        send("QUIT" + END_FLAG, out);
        response(in);
        in.close();
        out.close();
        socket.close();
    }

    public static void response(InputStream in) throws Exception {
        byte[] buffer = new byte[102400];
        int n = in.read(buffer);
        if(n>0){
            String s = new String(buffer, 0, n);
            System.out.println(s);
        }
    }

    public static void send(String s, OutputStream out) throws Exception {
        byte[] buffer = s.getBytes();
        if(buffer != null && buffer.length>0)
        {
            out.write(buffer);
            out.flush();
        }
    }
}