一、邮箱常用协议

邮箱中常用三类协议

POP3
- Post Office Protocol version 3
- **用于获取邮件。**适用于离线访问，客户端从服务端同步了一份数据。实际是两份数据。
- 适合离线访问
IMAP
- Internet Message Access Protocol
- **用于获取邮件。**适用于在线访问，客户端直接访问的服务端数据。实际是同一份数据。
- 适合多设备之间同步数据，比如邮件删除会所有设备都能同步。
SMTP
- Simple Mail Transfer Protocol
- 用于接收邮件

因此，想要实现一套邮箱服务，就要有收和发，那么就有两种组合方式

POP3/SMTP
IMAP/SMTP

二、阿里邮箱

2.1 配合域名使用阿里邮箱

此处针对阿里邮箱作为示例，简单记录一下。

2.2 代码示例

Java Maven 引入邮件依赖

<dependency>
    <groupId>com.sun.mail</groupId>
    <artifactId>javax.mail</artifactId>
    <version>1.6.2</version>
</dependency>

pop3

import javax.mail.*;
import java.util.Properties;

public class POP3Example {

    public static void list(String email, String emailPassword) {
        // POP3服务器连接属性
        Properties properties = new Properties();
        properties.setProperty("mail.store.protocol", "pop3");
        properties.setProperty("mail.pop3.host", "pop3.meethigher.top");
        properties.setProperty("mail.pop3.port", "110");
        properties.setProperty("mail.pop3.ssl.enable", "false");
        properties.setProperty("mail.debug", "true");
        Session session = Session.getInstance(properties);
        try (Store store = session.getStore("pop3")) {
            store.connect(email, emailPassword);
            // 打开收件箱
            Folder folder = store.getFolder("INBOX");
            folder.open(Folder.READ_ONLY);
            // 获取邮件
            Message[] messages = folder.getMessages();
            // 遍历处理邮件
            for (Message message : messages) {
                String sender = message.getFrom()[0].toString();
                String subject = message.getSubject();
                String content = message.getContent().toString();

                // 在这里处理邮件信息
                System.out.println("Sender: " + sender);
                System.out.println("Subject: " + subject);
                System.out.println("Content: " + content);
                System.out.println("------------------------------------");
            }
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("获取邮件失败");
        }
    }
}

imap

import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.Session;
import javax.mail.Store;
import java.util.Properties;

public class IMAPExample {

    public static void list(String email, String emailPassword) {
        // POP3服务器连接属性
        Properties properties = new Properties();
        properties.setProperty("mail.store.protocol", "imap");
        properties.setProperty("mail.imap.host", "imap.meethigher.top");
        properties.setProperty("mail.imap.port", "143");
        properties.setProperty("mail.imap.ssl.enable", "false");
        properties.setProperty("mail.debug", "true");
        Session session = Session.getInstance(properties);
        try (Store store = session.getStore("imap")) {
            store.connect(email, emailPassword);
            // 打开收件箱
            Folder folder = store.getFolder("INBOX");
            folder.open(Folder.READ_ONLY);
            // 获取邮件
            Message[] messages = folder.getMessages();
            // 遍历处理邮件
            for (Message message : messages) {
                String sender = message.getFrom()[0].toString();
                String subject = message.getSubject();
                String content = message.getContent().toString();

                // 在这里处理邮件信息
                System.out.println("Sender: " + sender);
                System.out.println("Subject: " + subject);
                System.out.println("Content: " + content);
                System.out.println("------------------------------------");
            }
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("获取邮件失败");
        }
    }
}

smtp

import javax.mail.*;
import javax.mail.internet.*;
import java.util.Properties;

public class SMTPExample {

    public static void send(String email, String emailPassword, String targetEmail) {
        // SMTP服务器连接属性
        Properties properties = new Properties();
        properties.setProperty("mail.smtp.host", "smtp.meethigher.top");
        properties.setProperty("mail.smtp.port", "80");
        properties.setProperty("mail.smtp.auth", "true");// 设置smtp是否需要认证
        properties.setProperty("mail.smtp.ssl.enable", "false");// 设置是否使用ssl安全连接 ---一般都使用
        properties.setProperty("mail.debug", "true");// 设置是否显示debug信息 true 会在控制台显示相关信息
        Session session = Session.getInstance(properties);
        try (Transport transport = session.getTransport()) {
            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress(email));
            message.setRecipient(Message.RecipientType.TO, new InternetAddress(targetEmail));
            message.setSubject("JavaMail SMTP Example");
            message.setText("This is a test email sent from JavaMail API.");
            transport.connect(email, emailPassword);
            transport.sendMessage(message, message.getAllRecipients());
            System.out.println("邮件发送成功");
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("邮件发送失败");
        }
    }
}