Java EE (Java Enterprise Edition) General Discussion

I'm trying to test sending an email and I get the following error ar Runtime:

java.lang.NoClassDefFoundError: com/sun/mail/util/MailDateFormat
at JavaMailTest.SendMail.postMail(SendMail.java:33)
at JavaMailTest.SendMail.main(SendMail.java:63)
Exception in thread "main"

The line that causes this exception is:
Session session = Session.getDefaultInstance(props, null);
===> Message msg = new MimeMessage(session);

Why is the MimeMessage class looking for MailDateFormat in com.sun.mail.util when this class only exists in javax.mail.internet(at least in mail.jar,mailapi.jar).

Am I missing something here? Any help appreciated.

thanks,
Peter