All employees can communicate with a patient via Messages as long as the patient has access to RevolutionPHR (i.e. patient portal, PHR). The patient can respond directly to that employee using the "Reply" feature within the message that was sent by the employee. The employee must have initiated the communication AND the patient must use "Reply."
Patients can create a NEW message to PROVIDERS listed within your practice's locations. A provider is anyone that has "Employee is also a provider" selected within their Employee file (access Admin > Employee/Roles > Employees > open the employee > Provider Details). Patients cannot create a new message to non-provider employees or specific user roles.