I am using Office 2010 (64 bit) and Windows 7 (64 bit) and the email PDF function does not work with EndNote x7.
This is unfortunate because it would be nice to email references within EndNote
Emailing a pdf/reference works fine for me under the same configuration.
Which email program are you using (and presumably it meets the requirements noted in
http://endnote.com/kb/128110 from the knowledge base).
What happens when you select a reference then click “E-mail Reference”?