Spring Boot使用GMX发送邮件遇TLS握手错误求助

我尝试使用Spring Boot发送邮件，选用GMX作为邮件服务商，但控制台出现以下错误：

Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed: org.springframework.mail.MailSendException: Mail server connection failed. Failed messages: javax.mail.MessagingException: Could not convert socket to TLS;
nested exception is:
javax.net.ssl.SSLHandshakeException: No appropriate protocol (protocol is disabled or cipher suites are inappropriate); message exceptions (1) are:
Failed message 1: javax.mail.MessagingException: Could not convert socket to TLS;
nested exception is:
javax.net.ssl.SSLHandshakeException: No appropriate protocol (protocol is disabled or cipher suites are inappropriate)] with root cause

javax.net.ssl.SSLHandshakeException: No appropriate protocol (protocol
is disabled or cipher suites are inappropriate)

核心代码：

@Autowired
private JavaMailSender javaMailSender;


private void sendMail() {
    
     SimpleMailMessage msg = new SimpleMailMessage();
     msg.setTo("to_1@gmail.com", "to_2@gmail.com", "to_3@yahoo.com");

     msg.setSubject("Testing from Spring Boot");
     msg.setText("Hello World \n Spring Boot Email");

     javaMailSender.send(msg);
   
}

pom.xml配置：

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-context-support</artifactId>
    <version>5.2.8.RELEASE</version>
</dependency>
<dependency>
    <groupId>javax.mail</groupId>
    <artifactId>mail</artifactId>
    <version>1.4.7</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-mail</artifactId>
</dependency>

application.properties配置：

spring.mail.protocol=smtp
spring.mail.host=mail.gmx.net
spring.mail.properties.mail.smtp.ssl.trust=mail.gmx.net
spring.mail.port=587
spring.mail.username=XYZ@gmx.de
spring.mail.password=xyz
# Other properties
spring.mail.properties.mail.smtp.auth=true
spring.mail.properties.mail.smtp.connectiontimeout=5000
spring.mail.properties.mail.smtp.timeout=5000
spring.mail.properties.mail.smtp.writetimeout=5000
# TLS , port 587
spring.mail.properties.mail.smtp.starttls.enable=true

问题原因与解决步骤 #

核心原因 #

错误根源是：JVM默认禁用了GMX兼容的旧版TLS协议（如TLSv1.2），同时pom.xml中存在邮件依赖版本冲突，导致协议协商失败。

解决步骤 #

1. 清理冗余依赖
   spring-boot-starter-mail已经封装了邮件发送所需的所有依赖，不需要单独引入javax.mail和spring-context-support。修改pom.xml，只保留核心依赖：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-mail</artifactId>
</dependency>

2. 强制指定TLS协议版本
   在application.properties中添加配置，明确指定GMX支持的TLSv1.2协议，同时强制开启STARTTLS：

spring.mail.properties.mail.smtp.ssl.protocols=TLSv1.2
spring.mail.properties.mail.smtp.starttls.required=true

3. 验证GMX账户配置

• 确认GMX账户已开启SMTP服务（GMX默认开启，但需检查账户设置）
• 若开启了两步验证，必须使用应用专用密码替代原登录密码，否则会验证失败

4. JVM安全配置调整（可选）
   如果上述配置仍无效，需修改JRE目录下的lib/security/java.security文件：

• 找到jdk.tls.disabledAlgorithms配置项，移除其中的TLSv1.2（若存在）
• 重启应用生效

最终完整配置示例 #

修改后的application.properties：

spring.mail.protocol=smtp
spring.mail.host=mail.gmx.net
spring.mail.port=587
spring.mail.username=XYZ@gmx.de
spring.mail.password=你的应用专用密码（开启两步验证时使用）
spring.mail.properties.mail.smtp.auth=true
spring.mail.properties.mail.smtp.connectiontimeout=5000
spring.mail.properties.mail.smtp.timeout=5000
spring.mail.properties.mail.smtp.writetimeout=5000
spring.mail.properties.mail.smtp.starttls.enable=true
spring.mail.properties.mail.smtp.starttls.required=true
spring.mail.properties.mail.smtp.ssl.trust=mail.gmx.net
spring.mail.properties.mail.smtp.ssl.protocols=TLSv1.2

内容的提问来源于stack exchange，提问作者Captai-N