pom文件里加入spring-boot-starter-mail依赖

        <!--SpringBoot邮件服务-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-mail</artifactId>
        </dependency>

application.properties里加入配置，这边使用163邮箱http://www.zeromemos.com/index/article/read.html?id=232

spring.mail.host=smtp.163.com
spring.mail.username=zjcnhs123@163.com
spring.mail.password=XXXXX
spring.mail.default-encoding=UTF-8
# 启动ssl
spring.mail.properties.mail.smtp.ssl.enable=true

# 启动tls
spring.mail.properties.mail.smtp.starttls.enable=true
spring.mail.properties.mail.smtp.starttls.required=true
spring.mail.properties.mail.smtp.connectiontimeout=5000
spring.mail.properties.mail.smtp.timeout=3000
spring.mail.properties.mail.smtp.writetimeout=5000

创建邮件服务接口MailService和实现类MailServiceImpl

package com.zeromemos.service;

public interface MailService {
    void sendSimpleMail(String to, String subject, String content);
}

package com.zeromemos.service.impl;

import com.zeromemos.service.MailService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.mail.SimpleMailMessage;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.stereotype.Service;

@Service
public class MailServiceImpl implements MailService {

    @Autowired
    JavaMailSender javaMailSender;

    @Value("${spring.mail.username}") //直接从配置文件获取username的值
    private String from;

    @Override
    public void sendSimpleMail(String to, String subject, String content) {

        // 简单邮件可以直接构建一个SimpleMailMessage对象进行配置，配置完成后，通过JavaMailSender将邮件发送出去。
        SimpleMailMessage simpMsg = new SimpleMailMessage();
        simpMsg.setFrom(from);//发送者
        simpMsg.setTo(to);//收件者
        //simpMsg.setCc(cc);//抄送人
        simpMsg.setSubject(subject);//主题
        simpMsg.setText(content);//内容
        javaMailSender.send(simpMsg);
    }
}

到控制器里加入测试代码

    @Autowired
    private MailService mailService;

    @GetMapping("/send/{to}")
    public R send(@PathVariable String to){
        String subject = "邮件主题:XXX";
        String content = "邮件内容:XXX";
        mailService.sendSimpleMail(to, subject, content);
        return R.ok();
    }

访问http://localhost:8001/send/xxxx@qq.com，后面跟你的测试接收邮箱

接收成功