将spring boot3项目部署到阿里云服务器运行，发送邮件时报错 Could not connect to SMTP host: smtp.qq.com, port: 25, response: -1

原因

阿里云服务器出于安全策略的考虑，主动屏蔽了服务器25端口，导致邮件服务无法正常使用。

解决办法

重新编写自定义JavaMailSenderImpl，并注册为Bean，邮件的端口改为 465

@Bean
    public JavaMailSenderImpl mailSender(MailProperties mailProperties) {
        JavaMailSenderImpl javaMailSenderImpl = new JavaMailSenderImpl();
        javaMailSenderImpl.setHost(mailProperties.getHost());
        javaMailSenderImpl.setUsername(mailProperties.getUsername());
        javaMailSenderImpl.setPassword(mailProperties.getPassword());
        javaMailSenderImpl.setDefaultEncoding(StandardCharsets.UTF_8.name());
        javaMailSenderImpl.setPort(mailProperties.getPort());
        if (mailProperties.getPort() == 465) {
            Properties properties = new Properties();
            properties.put("mail.smtp.ssl.enable", true);
            javaMailSenderImpl.setJavaMailProperties(properties);
        }
        return javaMailSenderImpl;
    }

上传服务器运行，出现如下错误

只需在@Configuration下添加 @Import(MailProperties.class) 把属性导入进来就行了

第二种方案（本人没有测试，貌似原理差不多）

直接在 application.yml 中添加如下配置

spring:
  # SpringMail发送邮件相关配置
  mail:
    # 发送邮件的账号名
    username: [email protected]
    # 授权码
    password: xxxxxxxxxxxx
    # smtp服务主机  qq邮箱的服务主机为smtp.qq.com
    host: smtp.qq.com
    # 服务协议
    protocol: smtp
    # 编码集
    default-encoding: UTF-8
    # 服务端口
    port: 465
    properties:
      mail:
        smtp:
          auth: true
          socketFactory:
            port: 465
            class: javax.net.ssl.SSLSocketFactory   //这里可能有问题springboot3内置的是tomcat10，依赖包名应该是jakarta
            fallback: false
          starttls:
            enable: true
            required: true