Hi Erin,

Sorry, but you cannot attach additional files when emailing Invoices, Statements or any other 'email-able' document in Adagio. The only attachment with be a PDF of the invoice itself.

Additional information could be entered into the body of the email (as text only, not an attachment) from the Edit Email Covers function.

You could also put a URL web link into the email cover sheet, if your flyer is accessible on your website, which would allow your client to see the flyer, save attachment space, and avoid your customer not getting the attachment due to file size or other security considerations.