Hello there, @davenagel.

I can see how important to be able to fix the issue you've been experiencing, where most of your customers, not being able to receive their invoices through email. No worries, I'm glad to be of assistance today so this gets sorted out.

First, let's your email address. To do so:

1. Sign in to your QuickBooks Online (QBO) account.
2. Go to the Gear icon then select Account and settings.
3. Go to Company, and click on the Pencil icon to edit in the Contact info section.
4. Review each email address and make changes as needed.
5. Don't forget to hit on Save once done.

If your customers still can't receive the email, let's proceed and clear and re-enter your email address:

1. Click on the Gear icon then select Account and settings.
2. Go to the Company section, then click on the Pencil to edit the Contact info.
3. Clear the Company email field and enter the desired address as is, even if it appears correct. Be sure not to use any extra characters or spaces before, within, or after the address you enter.
4. Select Save, then Done.
5. Send yourself a test transaction. If you still don't receive the email, try using a different email address that has a different domain.

If the issue still persists, we can proceed to solution 3 which can be found in this article: 3 solutions for you when customers aren't receiving your emails.

On the other hand, if resetting the email address doesn’t work, I'd suggest adding Intuit as a trusted site to prevent your browser from potentially blocking site content.

Additionally, feel free to check on this article in case you'd like to customise a report in QBO to show the status of your invoices: Customise reports in QuickBooks Online.

As always, you can get back here anytime if you need further assistance with regard to invoices in QBO. Take care and have a wonderful day!