Think of the <CFMAIL> tag as ColdFusion's database-to-mail or Web-to-mail gateway. By using it in your pages, you can use all the data-collection and processing features of ColdFusion to manage mail that gets sent to one or more users. The tag can serve as simple a use as a mail processor for a form (mimicking CGI programs like mailto.exe), or as complex a use as a complete autoresponder and mailing-list manager.
<CFMAIL> is most often used within action pages, getting its required data from a form. To actually send mail, it works with either your network's existing mail (or SMTP) server or with a remote mail server to which your system has access.