Automated Workflow Emails, No Attachment Option for Invoice Templates

Automated Workflow Emails, No Attachment Option for Invoice Templates

You can send an invoice as an attachment to email recipients manually. Am I correct in saying that you can't send the same attachment when sending email templates automatically using workflow rules? Please tell me I'm wrong. I want to automatically send a sales order out to various people when it's approved. Seems basic. I'm finding that I can't do so as an attachment, nor as line items within an email template.