I tried to exchange emails with a customer. Why does it say email hidden?

Email addresses are hidden to protect your privacy. Additionally, project information that is captured on the Science Exchange order page serves as an audit trail. With that said, please feel free to exchange phone numbers and set up a phone calls. After the call, please capture details of the conversation on the order page, such as changes in the project scope, statement of work, or deliverables, to maintain the audit trail.