Design and implement a system for managing email customer service. Incoming mail goes to a common pool. There is a set of customer service agents who reply to email. If the email is part of an ongoing series of replies $($tracked using the in$-$reply$-$to field of email$)$ the mail should preferably be replied to by the same agent who replied earlier. The system should track all incoming mail and replies, so an agent can see the history of questions from a customer before replying to an email.