When using the default email template to send purchase orders, subcontracts, SCO's, etc. the recipient's email address is not included within the contact information or PO information (sample snip attached).
The only way to get this information included with the email is to also Cc the original recipient, which involves extra clicks and is easily forgotten. If anyone receiving a copy of the PO wants to contact the person on the Attention line, they must already know that person's email address or look it up, which is time consuming and would not be necessary if it had been included when the PO was sent out.