I am trying to email my invoices, and they are not showing "sent" on my end. How do I know if the customer has received it?

Hello there, 

It's great to have you connect with us here again. I'll be glad to share more info so you're on the right track with your work. QuickBooks is a user-friendly program that offers endless capabilities to the way you manage your accounting. 

The program makes it easy for you to know the status of the invoices. This allows you to learn more about where the invoice is at during your transaction with your customer. Here’s a few common statuses that you might see on invoices:

• Open: the invoice has an open balance.
• Not sent: you created the invoice, but didn’t send it to the customer.
• Sent: you emailed the invoice to the customer.
• Viewed: your customer opened the invoice.
• Partially paid: your customer made a partial payment
• Paid: your customer paid the invoice in full.
• Deposited: the bank deposit for the invoice payment is recorded in QuickBooks.
• Not deposited: the invoice is paid, but the bank deposit isn’t recorded in QuickBooks.
• Undelivered or Delivery error: the invoice was undelivered. Check the email address and resend from QuickBooks Online in your web browser.
• Voided: the invoice was voided in QuickBooks.

To answer your question above, you'll know that your customer has received an invoice when it shows aid on your end. In case there's an issue with delivering the invoice, QuickBooks will display a Deliver error status. 

Let me know if the info above helps. I'm here to help you achieve your goals.