How do I mark an invoice as Sent when printing and mailing?

Hi there, @happyleelawncare. 

Thank you for choosing QuickBooks as your accounting tools. I can walk you through how to mark an invoice as sent in QuickBooks Online.

You would need to send the invoice to a dummy email or to yourself in order to change the status to Sent. This is the workaround we can use to get the outcome you wanted.

Here’s how: 

1. Go to Sales from the left menu and select Customers.
2. Tap the customer name. Then locate and open the invoice.
3. Enter your email address on the right side of the customer name.
4. Click Save and send.
5. Press Save and close. 

Once done, you’ll find the invoice marked as Sent. You may check out this article for your reference: Send an invoice. 

Just in case you need some helpful references in the future, you can always visit our site: Help articles for QuickBooks Online.

This should get you on your way to marking the invoices as sent. Let me know if you have other questions about invoice transactions. I'm always here to help. Have a great day!