https://blog.csdn.net/qq_16055765/article/details/79740685
https://www.jianshu.com/writer#/notebooks/36543162/notes/49730902/preview

pom.xml

<dependency>
   <groupId>com.sun.mail</groupId>
   <artifactId>javax.mail</artifactId>
   <version>1.5.5</version>
</dependency>

application.yml

mail:
  account: 853671516@qq.com
  password: uxnsnlrujufobfdg
  transport:
    protocol: smtp
  smtp:
    auth: true
    port: 465
    host: smtp.qq.com
    socketFactory:
      class: javax.net.ssl.SSLSocketFactory
      fallback: false

SendSMS.java

package com.vegetables.web.utils;

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Service;

import javax.mail.Message;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import java.util.Properties;

@Slf4j
@Service
public class SendSMS {
    //发件人邮箱
    @Value("${mail.account}")
    private String ACCOUNT;
    //发件人密钥
    @Value("${mail.password}")
    private String PASSWORD;

    @Value("${mail.smtp.port}")
    private String PORT;

    @Value("${mail.smtp.host}")
    private String HOST;

    @Value("${mail.smtp.auth}")
    private String AUTH;

    @Value("${mail.transport.protocol}")
    private String PROTOCOL;

    @Value("${mail.smtp.socketFactory.class}")
    private String CLASS;

    @Value("${mail.smtp.socketFactory.fallback}")
    private String FALLBACK;

    //异步方法，另起线程
    @Async
    public void senEmail(String emailAddress, String emailMessage) throws Exception {
        log.info("Thread - {}", Thread.currentThread().getName());
        Properties props = new Properties();
        props.setProperty("mail.transport.protocol", PROTOCOL);
        props.setProperty("mail.smtp.host", HOST);
        props.setProperty("mail.smtp.auth", AUTH);
        props.setProperty("mail.smtp.port", PORT);
        props.setProperty("mail.smtp.socketFactory.class", CLASS);
        props.setProperty("mail.smtp.socketFactory.fallback", FALLBACK);
        props.setProperty("mail.smtp.socketFactory.port", PORT);

        log.info("prop - {}", props);

        Session session = Session.getInstance(props);
        session.setDebug(true);
        MimeMessage message = createMimeMessage(session, ACCOUNT, emailAddress, emailMessage);
        Transport transport = session.getTransport();
        transport.connect(ACCOUNT, PASSWORD);
        transport.sendMessage(message, message.getAllRecipients());
        transport.close();
    }

    private static MimeMessage createMimeMessage(Session session, String account, String mailAddress, String emailMessage) throws Exception {
        MimeMessage message = new MimeMessage(session);
        message.setFrom(new InternetAddress(account, "来自星星的亲切问候", "UTF-8"));
        message.addRecipient(Message.RecipientType.TO, new InternetAddress(mailAddress, "我的测试邮件_收件人昵称", "UTF-8"));

        MimeBodyPart text = new MimeBodyPart();
        text.setContent(emailMessage, "text/html;charset=UTF-8");
        MimeMultipart mm = new MimeMultipart();
        mm.addBodyPart(text);
        message.setContent(mm);
        message.setSubject("通知邮件", "UTF-8");
        return message;
    }
}