What version of Xataface are you using?
The Email module (version 0.1.x) does not include anything in the Email.php file. It is just a placeholder. The newer versions 0.2.x and 0.3.x (which only work with Xataface 2.0 or higher unfortunately) are virtually complete rewrites and do include content in these files.
The latest email module SVN can be viewed at
http://weblite.ca/svn/dataface/modules/Email/trunkDocumentation at
http://xataface.com/dox/modules/Email/latestVersion 0.1.x requires you to set up a cron job to handle the actual sending of the email. The newer versions don't require this (email is sent directly in the web server process). The newer version (0.3.x) also includes many other features such as templates, improved mail-merge, file attachments, and better support for Mime HTML emails.
I know this is sort of like dangling candy that you can't have because 2.0 isn't released yet... but it's coming.
-Steve