Newbie Class Loader Errors on javax/mail/Part

Question

I'm a newb to Java but have experience in other languages. I built a command line application using Eclipse 3.0 that runs great in Eclipse. The app takes incoming .eml files from a WinXP server's drop dir, parses the attachments and stashes them as blobs in a database. I've jarred my .class files together and set my Class-Path attributes in the Manifest file and the proggie looks like it wants to run until I get to line 102 in main() where I call on one of my helper classes.
The line reads:
MimeWalker objMime = new MimeWalker();
In my MimeWalker class upon instantiation, I have the initialization routine set up some class objects as follows:
public class MimeWalker {
     private int w;
     private boolean headerParsed;
     private String subject;
     private Address from;
     private Address to[];
     private Date sentDate;
     private InputStream bodyCopy;
     private String bodyMimeType;
     private Properties props;
     private Session mailSession;
     private MimeMessage message;
     private Multipart mPart;
     private int partCount;
     private String partContentType;
     private String partDisposition;
     private String partFilename;
     private String partMimeType;
     private InputStream partData;
     /* This method sets the private variables to the necessary values
     * to open a file at this point.
     public MimeWalker(){
          this.props = System.getProperties();
          this.props.put("mail.host", "smtp.dummydomain.com");
          this.props.put("mail.transport.protocol", "smtp");
          this.mailSession = Session.getDefaultInstance(this.props, null);
I have imported javax.mail.*; and javax.mail.internet.*; in my MimeWalker class and since this is the first point in the program where a call to that library is used this is where it's bombing. The bomb message I get is as follows:
Exception in thread "main" java.lang.NoClassDefFoundError: javax/mail/Part
at com.jwt.emailProc.EmailProcessor.main(EmailProcessor.java:102)
I've been dealing with this off anf on for almost 2 days now and have searched countless websites for some insight. I have two hypothesis at this point but don't know how valid either is.
1. javax/mail/Part is actually an Interface and not a class so could that be causing my problems? If so how?
2. Because the mail API relys on the activation.jar library there's some anomaly that is preventing it from working properly. activation.jar just like all the other necessary libraries are located in ./stuff/*.jar in relation to my emailProc.jar application.
Thanks in advance for any help you can provide!
--James                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

Answer 1

I found out what my problem was. So for all you Java newbs like me remember this!
In the MANIFEST.MF file if you have a line that is longer than 72 bytes (not characters... bytes) the end of the line is scrapped.
That was my problem. As soon as I broke my Class-Path line down into 3 seperate lines with each line starting with a single space and each previous line ending with a single space and cr my app just started working.
The JAR tutorial on this site is a great resource! I advise anyone attempting to Jar their distributions to use it.
-- James