I am not sure what you mean. The client you were planning to use does use an SMTP server of some sort. It may be a local one right within the client or it may be relaying it somehow, but there has to be an SMTP server of some sort.
Database mail works with pretty much any SMTP server. So you could configure any windows server with IIS and SMTP through the windows components installer. The companies I have worked for have always used Exchange, Lotus Notes, or some other email system (hosted locally) and I database mail would be configured to simply use the SMTP server on one of these servers. This is typically more secure than just turning on SMTP on a web server somewhere and using it to send email.