I' can walk you through how you can set up multiple emails in QuickBooks Online for your customer, @joe-tintcentral-.
The statements and invoices will go to the email address entered in the customer profile. However, at this moment, we're unable to indicate where a certain email address would go.
A new email address can also be added to the customer profile. To separate the primary and office email accounts, use a comma. Here's how:
Open the Sales menu and go to the Customers tab.
Locate the customer to whom you want to add multiple emails to. Click to open it.
Click the Edit button.
In the Email box, fill in the new email address (separated by a comma).
Once done, click on Save.
Please refer to the photos below:
Do this to the rest of your customers. When you send a statement (or any transaction), it will be sent to the main and the accounting office email addresses.