这个邮件发送系统，之前一直都比较好用。现在却不能发送了。大侠们帮忙啊！


String dns = "dns://";
   //得到接受方的服务器域名
   String domain = mesg.getTo().substring(mesg.getTo().indexOf('@') + 1);
   System.out.println("执行：得到域名："+domain);
   Hashtable env = new Hashtable();
   System.out.println("执行2");
   env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.dns.DnsContextFactory");
   System.out.println("执行3");
   env.put(Context.PROVIDER_URL, dns);
   System.out.println("执行4");
   DirContext ctx = new InitialDirContext(env);
   System.out.println("执行5");
   Attributes attrs =null;
   System.out.println("执行6");
   try{
   System.out.println("执行7");
   attrs = ctx.getAttributes(domain, new String[] {"MX"});
   System.out.println("执行8");
   }catch(NamingException e){
   e.printStackTrace();
   }catch(Exception e){
   System.out.println("执行9");
   e.printStackTrace();
   }
   System.out.println("执行：attrs："+attrs+"//attrs.size()//"+attrs.size());
   if (attrs == null || attrs.size() <= 0) {
   System.out.println("执行6");
       throw new java.lang.IllegalStateException("错误:你的DNS服务器没有相应的MX记录!");
   }
   NamingEnumeration servers = attrs.getAll();
   // 列出所有邮件服务器：
   String smtpHost = null;
   boolean isSend = false;
   StringBuffer buf = new StringBuffer();
   while (servers.hasMore())
   {
       Attribute hosts = (Attribute) servers.next();
       for (int i = 0; i < hosts.size(); ++i)
       {
           smtpHost = (String) hosts.get(i);
           smtpHost = smtpHost.substring(smtpHost.lastIndexOf(' ') + 1);
           try{
            System.out.println("执行：smtpHost："+smtpHost+"//mesg//"+mesg);
               sendEms(smtpHost, mesg);
               isSend = true;
               return;
           }catch(Exception e){
               e.printStackTrace();
               buf.append(e.toString()).append("\r\n");
               continue;
           }
       }
   }
   System.out.println("执行：isSend："+isSend);
   if (!isSend) {
       throw new java.lang.IllegalStateException("错误:发送失败," + buf.toString());
   }这个邮件发送系统，之前一直都比较好用。现在却不能发送了。大侠们帮忙啊！
异常如下：
javax.naming.OperationNotSupportedException: DNS service refused [response code 5]; remaining name 'qq.com'
at com.sun.jndi.dns.DnsClient.checkResponseCode(Unknown Source)
at com.sun.jndi.dns.DnsClient.isMatchResponse(Unknown Source)
at com.sun.jndi.dns.DnsClient.doUdpQuery(Unknown Source)
at com.sun.jndi.dns.DnsClient.query(Unknown Source)
at com.sun.jndi.dns.Resolver.query(Unknown Source)
at com.sun.jndi.dns.DnsContext.c_getAttributes(Unknown Source)
at com.sun.jndi.toolkit.ctx.ComponentDirContext.p_getAttributes(Unknown Source)
at com.sun.jndi.toolkit.ctx.PartialCompositeDirContext.getAttributes(Unknown Source)
at com.sun.jndi.toolkit.ctx.PartialCompositeDirContext.getAttributes(Unknown Source)
at javax.naming.directory.InitialDirContext.getAttributes(Unknown Source)
at action.SendMailGUI.sendMail(SendMailGUI.java:73)
at action.SendMailGUI.run(SendMailGUI.java:47)
at action.SendEmailAction.execute(SendEmailAction.java:98)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:441)
at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:280)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:243)
at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252)
at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:179)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:130)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:165)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:179)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:488)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Unknown Source)