//发件

package com.sun.mail;

import java.io.UnsupportedEncodingException;
import java.util.Properties;

import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

public class SendMail2 {
    public static void main(String[] args) throws UnsupportedEncodingException {
        boolean isSSL = true;
        String host = "smtp.163.com";
        int port = 465;
        String from = "发件人地址";
        String to = "收件人地址";
        boolean isAuth = true;
        final String username = "发件人地址";
        final String password = "发件人地址密码";

        Properties props = new Properties();
        props.put("mail.smtp.ssl.enable", isSSL);
        props.put("mail.smtp.host", host);
        props.put("mail.smtp.port", port);
        props.put("mail.smtp.auth", isAuth);

        Session session = Session.getDefaultInstance(props, new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(username, password);
            }
        });

        try {
            Message message = new MimeMessage(session);

            message.setFrom(new InternetAddress(from));
            message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));
            message.setSubject("测试邮件");
            message.setText("bingo!");

            Transport.send(message);
        } catch (AddressException e) {
            e.printStackTrace();
        } catch (MessagingException e) {
            e.printStackTrace();
        }

        System.out.println("发送完毕！");
    }
}

//收件

package com.sun.mail;

import java.io.IOException;
import java.util.Date;
import java.util.Properties;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.NoSuchProviderException;
import javax.mail.Session;
import javax.mail.Store;

public class FetchMail2 {
    public static void main(String[] args) throws IOException {
        String protocol = "pop3";
        boolean isSSL = true;
        String host = "pop.qq.com";
        int port = 995;
        String username = "收件人地址";
        String password = "收件人地址密码";//qq的现在需要用授权码

        Properties props = new Properties();
        props.put("mail.pop3.ssl.enable", isSSL);
        props.put("mail.pop3.host", host);
        props.put("mail.pop3.port", port);

        Session session = Session.getDefaultInstance(props);

        Store store = null;
        Folder folder = null;
        try {
            store = session.getStore(protocol);
            store.connect(username, password);

            folder = store.getFolder("INBOX");
            folder.open(Folder.READ_ONLY);

            int size = folder.getMessageCount();
            Message message = folder.getMessage(size);

            String from = message.getFrom()[0].toString();
            String subject = message.getSubject();
            Date date = message.getSentDate();

            System.out.println("From: " + from);
            System.out.println("Subject: " + subject);
            System.out.println("content:"+message.getContent());
            System.out.println("Date: " + date);
        } catch (NoSuchProviderException e) {
            e.printStackTrace();
        } catch (MessagingException e) {
            e.printStackTrace();
        } finally {
            try {
                if (folder != null) {
                    folder.close(false);
                }
                if (store != null) {
                    store.close();
                }
            } catch (MessagingException e) {
                e.printStackTrace();
            }
        }

        System.out.println("接收完毕！");
    }
}

java 邮件收发 (只能输入英文，中文需要转码)