A service installed when Internet Information Services (IIS) is installed on a computer running Microsoft Windows NT Server or Windows 2000 Server. The SMTP service is managed through a snap-in extension for the Microsoft Management Console (MMC) and is dedicated to the delivery of SMTP mail using the Simple Mail Transfer Protocol (SMTP).
The SMTP service has no facility for creating user mailboxes, so it cannot function as a stand-alone mail server. One common use for this service is to enable Active Server Pages (ASP) applications to send SMTP mail in response to a form submission.