java发送注册验证邮件的问题

用java mail发送用户注册验证邮件，邮件能正常发送，但是发送时，邮件中含有注册验证的超链接，不知道为什么系统会自动访问该超链接，以至于用户点击该超链接时，链接已失效？这是为什么？还请帮忙解答一下，我该如何做？以下是我的代码：

final String registerUrl = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/service/portal/user/emailVerify?userName=" + name +"&registerId=" + registerId.toString();

        final MimeMessagePreparator preparator = new MimeMessagePreparator() {  
               public void prepare(MimeMessage mimeMessage) throws Exception {  
                   MimeMessageHelper message = new MimeMessageHelper(mimeMessage,true,"UTF-8");  
                   message.setSubject("用户注册确认");  
                   message.setTo(email);  
                   message.setFrom("xxx@xxx.com");  
                   Map<String, Object> model = new HashMap<String, Object>();  
                   model.put("user", user);  
                   model.put("domain", registerUrl);
                   String text = VelocityEngineUtils.mergeTemplateIntoString(  
                   velocityEngine, "registration-confirmation.vm","UTF-8", model);  
                   message.setText(text, true);  
               }  
           };

           try{
            Thread thread = new Thread(){//异步发送邮件
                public void run(){
                    javaMailSender.send(preparator);
                }
            };
            thread.start();
           }catch(MailException e) {  
               e.printStackTrace();  
           }

具体发送邮件是在spring中配置的，用的是JavaMailSenderImpl，我看不出是哪儿的问题，麻烦帮忙看看。spring的配置如下：

<bean id="mailSender" class="org.springframework.mail.javamail.JavaMailSenderImpl">  
<property name="host" value="smtp.exmail.qq.com" />   
<property name="port" value="25" />   
<property name="username" value="xxx@xx.com" />   
<property name="password" value="xxx" />   
<property name="javaMailProperties">  
    <props>  
        <prop key="mail.smtp.auth">true</prop>   
        <prop key="mail.smtp.timeout">25000</prop>   
    </props>  
</property>