Code that uses Outlook.Application to initiate the email will only work with Outlook installed, but it isn't necessary for Outlook to be the default mail program. An alternative approach that should work on any Windows system, is to leverage the Windows Mail-API (aka MAPI). For some code to get you started on that, see:
http://www.vbaexpress.com/kb/getarticle.php?kb_id=311
See also:
http://www.vb-helper.com/howto_excel..._students.html