title: Lift Mailer error: gnu.mail.handler.TextPlain cannot be cast to javax.activation.DataContentHandler
body: <p>Using the following code:</p>
  
  <pre><code>
  sendMail(From(Props.get("email")), Subject("Test Email"), To("email@address"),
                     PlainMailBodyType("test email body"));
  </code></pre>
  
  <p>And in Boot.scala:</p>
  
  <pre><code>
   System.setProperty("mail.smtp.starttls.enable","false");
      System.setProperty("mail.smtp.host", host)
      System.setProperty("mail.smtp.auth", "true")
      Mailer.authenticator = Full(new Authenticator {
          override def getPasswordAuthentication = new PasswordAuthentication(user, password)
        })
  </code></pre>
  
  <p>I get the following error:</p>
  
  <p>2011-05-23 18:49:02,868 ERROR [pool-3-thread-4] n.l.u.MailerImpl [Logging.scala:239] Couldn't send mail
  java.lang.ClassCastException: gnu.mail.handler.TextPlain cannot be cast to javax.activation.DataContentHandler
          at javax.activation.MailcapCommandMap.getDataContentHandler(MailcapCommandMap.java:596) ~[activation-1.1.jar:1.1]
          at javax.activation.MailcapCommandMap.createDataContentHandler(MailcapCommandMap.java:550) ~[activation-1.1.jar:1.1]
          at javax.activation.DataHandler.getDataContentHandler(DataHandler.java:611) ~[activation-1.1.jar:1.1]
          at javax.activation.DataHandler.writeTo(DataHandler.java:315) ~[activation-1.1.jar:1.1]
          at javax.mail.internet.MimeUtility.getEncoding(MimeUtility.java:261) ~[mail-1.4.1.jar:1.4.1]
          at javax.mail.internet.MimeBodyPart.updateHeaders(MimeBodyPart.java:1321) ~[mail-1.4.1.jar:1.4.1]
          at javax.mail.internet.MimeMessage.updateHeaders(MimeMessage.java:2074) ~[mail-1.4.1.jar:1.4.1]
          at javax.mail.internet.MimeMessage.saveChanges(MimeMessage.java:2042) ~[mail-1.4.1.jar:1.4.1]
          at javax.mail.Transport.send(Transport.java:117) ~[mail-1.4.1.jar:1.4.1]
          at net.liftweb.util.MailerImpl$$anon$1$$anonfun$$init$$1.apply(Mailer.scala:176) ~[lift-util_2.8.1-2.3.jar:2.3]</p>
  
  <p>This code works on one box and not on another. Any ideas?</p>