How to set up SMTP services in XP

Our company is getting a Konica 7022 Multi-Function Copy System, one of which is scan to Email. Since we do not have a mail server in house and our ISP does not allow mail relaying we need to install an SMTP service for it to work. Since I have never used this service before I need some information on how to set it up for a small office of at least 15 users.