title: java.lang.LinkageError when trying to send email notification after completion of Jenkins job
body: <p>I am using Jenkins on Windows to run a nightly test suite for our company. One of the post-build steps I have configured is the Editable Email Notification. So far I have configured the following for the email notification:</p>
  <ul>
  <li>SMTP server set as smtp.gmail.com</li>
  <li>Default e-mail suffix set to company email suffix</li>
  <li>Username and password set for authentication (app password used since our company uses multi-factor authentication for Gmail accounts)</li>
  <li>Use SSL option checked, with port set to 465</li>
  <li>System admin email address set to same as reply-to address</li>
  </ul>
  <p>When running a test build, it succeeds and in the stack trace I see that both the connection and the authentication succeed (see examples from debug messages below):</p>
  <pre><code>DEBUG SMTP: connected to host &quot;smtp.gmail.com&quot;, port: 465
  DEBUG SMTP: AUTH LOGIN succeeded
  DEBUG SMTP: Verified Addresses
  354  Go ahead - gsmtp
  </code></pre>
  <p>However, immediately after it seems the email will be sent, I get the following error message:</p>
  <pre><code>ERROR: Step ‘Editable Email Notification’ aborted due to exception: 
  java.lang.LinkageError: 
  Caused: java.lang.BootstrapMethodError
      at io.jenkins.plugins.javax.activation.DelegatingCommandMap.createDataContentHandler(DelegatingCommandMap.java:64)
      at io.jenkins.plugins.javax.activation.DelegatingCommandMap.lambda$createDataContentHandler$6(DelegatingCommandMap.java:64)
      at io.jenkins.plugins.javax.activation.DelegatingCommandMap.runWithContextClassLoader(DelegatingCommandMap.java:26)
      at io.jenkins.plugins.javax.activation.DelegatingCommandMap.createDataContentHandler(DelegatingCommandMap.java:64)
      at javax.activation.DataHandler.getDataContentHandler(DataHandler.java:618)
      at javax.activation.DataHandler.writeTo(DataHandler.java:316)
      at javax.mail.internet.MimeUtility.getEncoding(MimeUtility.java:316)
      at javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1551)
      at javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1148)
      at javax.mail.internet.MimeMultipart.updateHeaders(MimeMultipart.java:498)
      at javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1509)
      at javax.mail.internet.MimeMessage.updateHeaders(MimeMessage.java:2238)
      at javax.mail.internet.MimeMessage.saveChanges(MimeMessage.java:2198)
      at javax.mail.internet.MimeMessage.writeTo(MimeMessage.java:1877)
      at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:1300)
      at hudson.plugins.emailext.ExtendedEmailPublisher.sendMail(ExtendedEmailPublisher.java:524)
      at hudson.plugins.emailext.ExtendedEmailPublisher._perform(ExtendedEmailPublisher.java:444)
      at hudson.plugins.emailext.ExtendedEmailPublisher.perform(ExtendedEmailPublisher.java:354)
      at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
      at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:806)
      at hudson.model.AbstractBuild$AbstractBuildExecution.performAllBuildSteps(AbstractBuild.java:755)
      at hudson.model.Build$BuildExecution.cleanUp(Build.java:188)
      at hudson.model.Run.execute(Run.java:1935)
      at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
      at hudson.model.ResourceController.execute(ResourceController.java:99)
      at hudson.model.Executor.run(Executor.java:432)
  </code></pre>
  <p>Any ideas on what might be causing this error?</p>