邮件发送的问题

我写了个发送邮件的程序!可是测试时我用163的服务器,发送地址和接受地址一样,可是他却报错!不知道是什么原因!谁能帮我看看啊!这是我写的Servlet:
public void doGet(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {
response.setContentType(CONTENT_TYPE);
PrintWriter out = response.getWriter();
String smtpServer = request.getParameter("txtserver");
String emailTo = request.getParameter("txtto");
String fromEmail = request.getParameter("txtfrom");
String subject = request.getParameter("txtsubject");
String body = request.getParameter("txtmessage");
try
{
Properties props = new Properties();
props.put("mail.transport.protocol","smtp");
props.put("mail.transport.host",smtpServer);
props.put("mail.transport.port","25");
Session mailsession = Session.getInstance(props);
Message msg = new MimeMessage(mailsession);

msg.setFrom(new InternetAddress(fromEmail));
msg.setRecipients(Message.RecipientType.TO,InternetAddress.parse(emailTo));
msg.setSentDate(new Date());
msg.setSubject(subject);
msg.setText(body);
Transport.send(msg);
msg.writeTo(System.out);
out.println("邮件已成功发送到："+emailTo);
}
catch(Exception me)
{
System.out.println(me);
}
out.close();
}
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错误信息是什么
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HTTP Status 500 -
HTTP Status 500 - type Exception reportmessage description The server encountered an internal error () that prevented it from fulfilling this request.exception javax.servlet.ServletException: Wrapper cannot find servlet class untitled29.Servlet1 or a class it depends on
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
java.lang.Thread.run(Thread.java:595)
root cause java.lang.ClassNotFoundException: untitled29.Servlet1
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1332)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1181)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
java.lang.Thread.run(Thread.java:595)
note The full stack trace of the root cause is available in the Apache Tomcat/5.5.9 logs.Apache Tomcat/5.5.9
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