JavaMail 发送问题探讨

代码如下

try {
Message rs = new MimeMessage(session);

Address from = new InternetAddress(this.address);
rs.setFrom(from);
rs.setSentDate(new Date());
// rs.setRecipient(RecipientType.TO, new InternetAddress(toAddress));
rs.addRecipient(Message.RecipientType.TO,new InternetAddress(toAddress));

rs.setSubject(subject);
Multipart mp = new MimeMultipart();
BodyPart html = new MimeBodyPart();
html.setContent(content, "text/plain");
mp.addBodyPart(html);
if (files != null && files.length > 0) {

for (int i = 0; i < files.length; i++) {
MimeBodyPart mbp = new MimeBodyPart();
FileDataSource fds = new FileDataSource(files[i]);
mbp.setDataHandler(new DataHandler(fds));
mbp.setFileName(MimeUtility.encodeWord(files[i], "GBK", null));
mp.addBodyPart(mbp);
}
}

//rs.setContent(mp);
rs.setContent(content, "text/plain");
rs.saveChanges();
// rs.setText("hello ,I love you");

Transport transport = session.getTransport("smtp");
transport.connect(server,username, password);
System.out.println(2.5);
if(rs!=null)
{
// transport.sendMessage(rs, rs.getAllRecipients());

transport.send(rs, rs.getAllRecipients());
System.out.println(3);
}
我发送时老有一个错误:
发生在transport.send()...
说NoClassDefFounderError:com/sun/activation/registries/LogSupport
但是我已经
import javax.activation.*;