How do I confirm receipt of my invoice? Is there a read receipt function?

Welcome to Community, @chriso1.

I have some information about the receipt function. While there isn't a confirm receipt function, you can view your receipts from the banking tab. Let me walk you through how.

1. Go to the Banking tab. Then, select the Receipts tab.
2. Choose a receipt to see more details.
3. If you see Review in the Action column, tick it to make corrections or add missing info.

From there you can categorize your expense into the right account. 

Here's a guide for details: Capture and categorize expense receipts and bills in QuickBooks Online.

If you need help with other tasks in QBO, click this link to go to our general topics with articles.

Keep me posted if you still have questions or concerns with receipts. I'll be around for you. Take care and have a wonderful day ahead.

Thank you, you answered my question there is no read receipt (similar to Outlook) option with QB to confirm my client actually received my invoice. I think that would be a great addition to the process.