title: java.lang.NoClassDefFoundError: javax/mail/MessagingException
body: <p>I've been working on a program that uses the Javamail API to send emails based on time events and certain conditions. The program runs perfectly in Eclipse (newest version) and the javamail and activator jars are in the build path, as are javamail's dependencies. The problem occurs when I export the project as a jar and try to run it. (The stack trace generated is the same that would be if the javamail jar was missing from the Eclipse build path). </p>
  
  <p>The stack trace is as follows: </p>
  
  <pre><code>`Exception in thread "Timer-1" java.lang.NoClassDefFoundError: javax/mail/MessagingException
  at SpaceCheck.HourlySpaceAlerts(SpaceCheck.java:212)
  at WarningReports.run(WarningReports.java:21)
  at java.util.TimerThread.mainLoop(Unknown Source)
  at java.util.TimerThread.run(Unknown Source)
  Caused by: java.lang.ClassNotFoundException: javax.mail.MessagingException
  at java.net.URLClassLoader$1.run(Unknown Source)
  at java.net.URLClassLoader$1.run(Unknown Source)
  at java.security.AccessController.doPrivileged(Native Method)
  at java.net.URLClassLoader.findClass(Unknown Source)
  at java.lang.ClassLoader.loadClass(Unknown Source)
  at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
  at java.lang.ClassLoader.loadClass(Unknown Source)
  ... 4 more`
  </code></pre>
  
  <p>Thank you for your help. </p>