Design a simple e-mail messaging system. A message has a recipient, a sender, and a message text. A mailbox can store messages. Supply a number of mailboxes for different users and a user interface for users to log in, send messages to other users, read their own messages, and log out. Follow the design process that was described in this chapter.

Complete the following files:

EmailMenu.java

EmailSimulation.java

Mailbox.java

Message.java

MessagingSystem.java