# 11.4. 发送电子邮件

Spring 框架提供了使用`JavaMailSender`接口发送电子邮件的抽象，Spring Boot 为其提供了自动配置以及启动模块。

> 有关如何使用 的详细说明， 请参阅[`JavaMailSender`参考文档](https://docs.spring.io/spring-framework/reference/6.1/integration/email.html)。

如果`spring.mail.host`和相关库（由`spring-boot-starter-mail` 定义）可用，则创建默认`JavaMailSender`（如果不存在）。发送者可以通过`spring.mail`命名空间中的配置项进一步定制。请参阅[`MailProperties`](https://github.com/spring-projects/spring-boot/tree/v3.2.0/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/mail/MailProperties.java)了解更多详情。

特别是，某些默认超时值是无限的，您可能需要更改该值以避免线程被无响应的邮件服务器阻塞，如以下示例所示：

```
spring.mail.properties[mail.smtp.connectiontimeout]=5000
spring.mail.properties[mail.smtp.timeout]=3000
spring.mail.properties[mail.smtp.writetimeout]=5000
```

还可以使用 JNDI 中的现有`Session`配置进行`JavaMailSender`配置：

```
spring.mail.jndi-name=mail/Session
```

设置`jndi-name` 后，它优先于所有其他与会话相关的设置。


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