I want to set up the quickbooks so that when I email an invoice it is automatically BCC to a third party.

Hello helen76,

Thanks for posting in the Community!

Let me guide you on how you can automatically email Blind copy (BCC) when sending invoices in QuickBooks Online. We can do that by setting it up in your Account & Settings. Here's how to:

1. Log in to your QuickBooks Online account.
2. Click on the Settings icon.
3. Click on Account & Settings.
4. Click on Sales tab, and then select the pencil icon under the Messages section.
5. Enter the email address you wish in the BCC field to receive a copy of the invoice.
6. Click on Save and then Done to confirm.

Check the sample invoice below for reference.

For reference you can also check this link to learn more on how to customise your sales forms: Customise invoices, quotes, and sales receipts in QuickBooks Online.

Feel free to post again in the Community if you have further concerns. I'm around to help you.