Can anyone help. Invoices are not sending - saying delivery issue, even though we have sent to the emails before.

Welcome to the QuickBooks Community, accounts526. I'll be providing details about being unable to send invoices. Then, let me help you perform some alternative steps as a workaround to ensure you can accomplish your goal.

The issue of invoices are not sending or having a delivery issue is tagged as an ongoing problem. Our team is aware of the matter and we're currently implementing measures to fix this issue. Please know that this is a high priority for us and will continue to be a focus until fully resolved.

For now, I recommend completing the steps below on how to send the invoices so your customers can receive those sales entries.

•  You can save your invoice as a PDF and send it via email through your business or other email address.
• You can send your customer a link to their invoice via SMS or messenger service. You'll have to click on save and share link and copy link and then, paste it into your SMS or messenger.
• You can save your invoice as a PDF and print it. Then, send your customer their invoice through email.

Then, I suggest contacting our QuickBooks Support Team if you haven't reached them. This is to ensure they can add you to our notification list. This will help our engineers determine the number of affected users. You'll also receive an update through email once this has been resolved.

Lastly, you may refer to this article to see details on how the Sales page helps you to view all sales transactions and invoice status at a glance: View sales transactions.

If you need further assistance regarding your QuickBooks Online sales transactions, you can always leave a comment below, RL89. I'm always here to help. Stay safe!