Talking from sendmail to Exchange over SMTP auth

There are various things you can do in Exchange, such as control who can address distribution lists, that can be restricted to authenticated senders only. So how do you make your sendmail box an authenticated sender?

Start at -- about half way down it starts talking about “Using sendmail as a client with AUTH”. That tells you how to setup your sendmail box (which is the client) so that it talks SMTP auth to Exchange (which is the server).