Hi LecaLeca,
Pages is not an email application. Email applications, including Mail, cannot open Pages documents, but can carry then as attachments (as they can carry other types of file).
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You can send the Pages document as an attachment, convert the Pages document to a PDF document, and send that as an attachment, export the Pages document as a Word document (or other document) and send that as an attachment.
Or you can copy the content of the Pages document and paste that content into an email message (which may take several steps if the Pages document contains both text and images or other objects), and send the email.
Be aware that unless the recipient is running a Mac (and unless that Mac has a compatible version of Pages installed), they will be unable to open or read the Pages version of the newsletter.
Mail (and many other email applications) will display a single page PDF document in the body of the message, so your best bet may be to print each page to a PDZF file, name the files to include the page number in the name, then attach the files to your message.
Regards,
Barry