Q: For both email notification and incoming email, I got an NPE on an Ubuntu linux:
     java.lang.NullPointerException
	at java.lang.String.concat(String.java:1827)
	at com.sun.activation.registries.MailcapFile.parseLine(MailcapFile.java:254)
	at com.sun.activation.registries.MailcapFile.parse(MailcapFile.java:216)
	at com.sun.activation.registries.MailcapFile.createMailcapHash(MailcapFile.java:176)
	at com.sun.activation.registries.MailcapFile.(MailcapFile.java:50)
	at javax.activation.MailcapCommandMap.loadFile(MailcapCommandMap.java:189)
	at javax.activation.MailcapCommandMap.(MailcapCommandMap.java:139)
	at javax.activation.CommandMap.getDefaultCommandMap(CommandMap.java:55)
	at javax.activation.DataHandler.getCommandMap(DataHandler.java:146)
	at javax.activation.DataHandler.getDataContentHandler(DataHandler.java:578)
	at javax.activation.DataHandler.getContent(DataHandler.java:511)
	at javax.mail.internet.MimeBodyPart.getContent(MimeBodyPart.java:531)

A: This is caused by the $HOME/.mailcap file.
   Deleting the file or 
   deleting the "-e" from the beginning of the file shall fix the problem.