Configure SMTP in Windows Server

We have a new Windows 2008 R2 server and we would like you to correctly configure SMTP server to be able to send e-mails from a software installed locally. We want to restrict acces from any external connection, only internal (local) unauthenticated connections will be able to send emails. We don't need TLS or anything fancy, in fact we don't need any authentication, but we don't want an open-relay or any security faults. Currently the server has all DNS and 1 MX record, we would like to only send emails from the server, the server doesn't need to receive (nor we want it to) emails. Please state your price, this will probably not take you more than 1 hour if you know what you are doing.