Hi there, @myfavoritehandym.

I can see the convenience of getting the authorization of your QuickBooks email to your Gmail.

The code Gmail has sent will not be seen because it's only within the system. It's the same if you're using the auto-forwarding setup in Gmail. I'd recommend uploading your receipts from your computer to your QuickBooks Online.

To know more about this feature, you can check out this article: Email receipts and bills to QuickBooks Online.

I've added this article that you may use on your future tasks about personalizing your sales forms: Customize invoices, estimates, and sales receipts in QuickBooks Online. This way, you'll be able to show through design or layout what your business offers.

I'll be here if you have other concerns or questions. Just let me know in the comment section below. Take care.