If I'm reading your statement correctly, you are emailing this as a Pages document, which is then opened by the recipient in Pages. Display of the sidebar is controlled by the application opening the document, if it's opened in Pages, then it is possible for the sidebar to be shown.
If you do not want the recipient to be able to see the sidebar, "Print" the document as a PDF file, and email that. The resulting PDF document will be opened by Preview, Adobe reader, or other PDF reader application not capable of opening the sidebar.
With the finished version of the Pages document open:
A new email document will open with the PDF file included as an attachment.
(To view the PDF, double click the attachment, which will launch Preview and display the document.)
Address the email, add any message to accompany the attachment, and send.