spring boot mail 发送邮件到自建服务器（采坑指南）

1. 引入依赖

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

2. 配置服务器地址

   spring:
     mail:
       host: mail.kcjz.com
       username: kcjz@kcjz.com
       password: kcjz
       port: 25
       properties:
   #      指定starttls加密
         mail:
           smtp:
             starttls:
               enable: true
   #            不认证ssl证书
             ssl:
               trust: mail.kcjz.com
   #            设置超时时间，默认是没有超时时间的
             connectiontimeout: 5000
             timeout: 3000
             writetimeout: 5000
   

   1. 需要指定加密方式是starttls，解决一下异常：

      org.springframework.mail.MailSendException: Failed messages: com.sun.mail.smtp.SMTPSendFailedException: 530 5.7.0 Must issue a STARTTLS command first
      
      ; message exception details (1) are:
      Failed message 1:
      com.sun.mail.smtp.SMTPSendFailedException: 530 5.7.0 Must issue a STARTTLS command first
      
        at com.sun.mail.smtp.SMTPTransport.issueSendCommand(SMTPTransport.java:2374)
        at com.sun.mail.smtp.SMTPTransport.mailFrom(SMTPTransport.java:1808)
        at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:1285)
        at org.springframework.mail.javamail.JavaMailSenderImpl.doSend(JavaMailSenderImpl.java:465)
        at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:323)
        at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:312)
      

   2. 对指定域名的ssl证书进行信任（ssl证书是自签发的服务器），解决以下异常：

      org.springframework.mail.MailSendException: Mail server connection failed; nested exception is javax.mail.MessagingException: Could not convert socket to TLS;
        nested exception is:
        javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target. Failed messages: javax.mail.MessagingException: Could not convert socket to TLS;
        nested exception is:
        javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
      ; message exception details (1) are:
      Failed message 1:
      javax.mail.MessagingException: Could not convert socket to TLS;
        nested exception is:
        javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at com.sun.mail.smtp.SMTPTransport.startTLS(SMTPTransport.java:2140)
        at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:734)
        at javax.mail.Service.connect(Service.java:342)
        at org.springframework.mail.javamail.JavaMailSenderImpl.connectTransport(JavaMailSenderImpl.java:518)
        at org.springframework.mail.javamail.JavaMailSenderImpl.doSend(JavaMailSenderImpl.java:437)
        at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:323)
        at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:312)
      

   3. 设置超时时间，默认是没有超时时间的

3. 测试代码

       @Test
       void mail(){
           //建立邮件消息
           SimpleMailMessage mainMessage = new SimpleMailMessage();
           //发送方
           mainMessage.setFrom("kcjz@kcjz.com");
           //接收方
           mainMessage.setTo("*********@qq.com");
           //发送的标题
           mainMessage.setSubject("测试邮件");
           //发送的内容
           mainMessage.setText("我只是个测试邮件");
           javaMailSender.send(mainMessage);
       }