How to export a PDF to Apple Mail or Microsoft Outlook
Select Share > Attach PDF to Email Message

A new mail message will be created with your document attached.
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Jeff Byers
What about those of us who do not use Apple Mail? What's the procedure to attache to an a message in Gmail, for instance?
Trevor DeVore
@Jeff - In order for Clarify to attach a PDF to an email there needs to be a desktop application. Gmail is a web application.