Ideally, you should be able to set the additional recipients in WooCommerce or in which ever plugin is creating the email. (i.e. in Ninja Forms / Gravity Forms, you would specify multiple recipients at that point). I’m pretty sure WooCommerce gives you the ability to have multiple recipients.
However, you also have the option of adding Additional Email Addresses with the Post SMTP Plugin, but the downside of that is ALL emails that are sent by the whole website will also be sent to those additional recipients. You only want details of any incoming orders to be sent to the purchaser and bookkeeper, you don’t want the Website “There is an update available for your site” which would normally be sent to you, to be also sent to your bookkeeper. Or a “There is a new comment on your site which needs moderating” which would also be sent to any additional addresses you specify.
The additional email addresses can be setting on the Post SMTP settings “Message” tab.
But as I mention above, this will send the addition emails for every single email that is sent by the site, not just the ones that WooCommerce generates.
If you cannot find the option in WooCommerce, you’d be best raising this question in the WooCommerce support forum.
Check the email options here: https://docs.woocommerce.com/document/configuring-woocommerce-settings/
There is also a WooCommerce plugin you can use to create additional notifications
https://docs.woocommerce.com/document/advanced-notifications/
“The Advanced Notifications extension for WooCommerce lets you set up order and stock notifications for users other than the admin user. These can be used for anything; notifying staff and users of sales, sending stock notices to suppliers, or even sending new orders to drop shippers.”
