Let’s perform some troubleshooting steps to ensure you can send invoices through Gmail, DJHANDYMAN20.
Before we proceed, could you please verify if you've encountered a specific error message?
In the meantime, I recommend clearing your browser’s cache to remove any stored data that may be causing issues with QuickBooks Online (QBO).
If the issue persists, you can use a different browser to check for compatibility and rule out browser-specific problems. After completing these steps, resend the invoice.
You can also follow the step 3, last bullet from this article: Send an invoice to a customer.
If you have questions or concerns, reply to this thread.