I have tried to send invoice 1018 4 times and am being told there is a delivery issue yet i am sending to a valid email address. please can you investigate

I wish you didn't have to resend your invoices multiple times, vernon-the-everi.

Did you receive a specific error message when attempting to send the invoices? This will help us verify if there's any existing investigation related to this.

In the meantime, let's access your QuickBooks Online account via a private window to determine if this is a browser-related issue.

Here are the keyboard shortcuts: 

• Safari: Command + Shift + N 
• Google Chrome: CTRL + Shift + N
• Mozilla Firefox or Microsoft Edge: CTRL + Shift + P 

After that, try sending an invoice. If it works, I'd recommend clearing the cache to improve the program's performance. You can also use other supported browsers as alternatives.

If the issue persists, I'd suggest checking with your clients if there's an issue with their email server that blocks any incoming emails.

For now, we can download the invoice and send it manually to your customer by attaching it to an email. Here's how:

1. Open the invoice you want to send. 
2. Select the Print or Preview button on the bottom part of the screen. 
3. Click the Download option. 
4.  Use your email provider and send them to your clients. 

I've also added this article that'll help you personalise the info of your invoices in QuickBooks Online: Customise Sales Forms.

Please keep us posted if you have any other questions or concerns about sending your sales transactions. We're always here to assist you. Keep safe!