This article shows you how to set up your workflow to send an e-mail message.
It also explains how to use workflow lookups both to address the mail and to
include dynamic content in the message body, including how to insert or build
hyperlinks. Finally, this article shows you how to format the content of the
message, along with providing other information about working with
workflow-generated e-mail messages.
The official party line from Microsoft, who usually do a fine job with online documentation.