mail exchange report

i would to know about the mail exchange and what r the requirements to have one, like do i need a server ( for example ) do i have to use online or local network? all i need is to show this report to a company and they tell me the price to have it. i need a report got all information about the mail exchange? cuz i have a big company and i need mail exchange in it , and each employ has his/her own email.