Set up in Magento
Click on Stores > Configuration > Sales > Sales Emails to get started. Individually configure every email type you see below with the pdf documents you want to automatically attach.
Standard Magento Settings
The first six settings are standard Magento settings - configure these as per normal.
Be sure to enable automatic sales emails.
Attach Invoice/Shipment/Credit Memo as Pdf (v1.0.0+)
When set to “Yes”, your invoice/shipment/credit memo pdf document will be automatically attached to the order/invoice/shipment/credit memo email.
Attach Order as Pdf (v1.0.0+)
You can also choose to automatically attach an order document to the order email. This requires the free Fooman Print Order Pdf extension - you’ll need to install this first in order for this feature to be enabled: Link to free download.
Attach Terms and Conditions (v1.0.0+)
When set to “Yes”, your Terms and Conditions html and text files (from Sales > Terms and Conditions) will be automatically attached to the email.