Your Message Box is like a personal emailing box where you will receive messages from other users of iKast. You can reach it by clicking on the MESSAGE menu in main bar.
The Messages screen will list different types of messages:
Request of connection from Partners that want to deal with you;
Request of Validation for Contracts proposed by your Partners;
Infringement cases detected by ikast;
Messages can require actions from you like accepting or rejecting a Contract Proposal or a Connection Request.
Tips: You can receive those messages also as emails if you activate this option in your Settings section.