The email infrastructure at KIT has been upgraded. Mailboxes are now hosted on Exchange 2013 servers. In the course of this upgrade, the design of the exchange system has been modernised. The servers are running on virtual machines in two clusters at both Campus Nord and Campus Süd. The databases are working with a geographical active/passive failover between the campuses. This setup enables on-line maintenance of the servers and a reliable stable infrastructure for our users.