I can get subject, from, date received and size, but I can't get the content. Futher more,the getHeader("Subject")
getHeader("From"),etc method will get null.It works if I use POP3 protocol to get the content

Here is the error message
java.lang.NullPointerException
at com.sun.mail.imap.IMAPMessage.getContentType(IMAPMessage.java:323)
at javax.mail.internet.MimeBodyPart.isMimeType(MimeBodyPart.java:802)
at javax.mail.internet.MimeMessage.isMimeType(MimeMessage.java:851)