Hi there, Amidge71.
Here are some steps you can follow to ensure that your customers receive their invoices on time.
First, have them check their junk or spam folder. Sometimes, invoices sent via QuickBooks Online (QBO) may be found in your customer's spam or junk folders, as automated emails can often be flagged by mail servers.
If it's still missing, we'll have to configure your email setup. Let me guide you with these steps:
- Go to the Gear icon and select Account and settings.
- Navigate to the Company tab.
- In the Contact Info window, click Edit in the Email section.
- Clear the Company email field and enter the desired address as is, ensuring it is typed correctly. Avoid adding any extra characters or spaces before, within, or after the email address.
- Select Save, then Done.

Then, send yourself a test transaction. If you still don't receive the email, try using a different email address that has a different domain.
You can refer to this article for more details on how to resolve the issue when your customers aren't receiving emails from QuickBooks Online: 3 solutions for when customers aren't receiving your emails.
In the meantime, you can manually download the invoice in PDF format and send it directly through your email (outside QBO) as a workaround while troubleshooting QBO-generated emails.
If a customer has paid an invoice but it is still marked as "not viewed" in QBO, they may have completed the payment without opening the invoice. To address this issue, verify that the payment details correspond to the correct invoice number.
Don't hesitate to leave a Reply below if there's anything else you need about customers not receiving invoices. We'll be right here to help you.