I'll give steps to resolve the issue, so you can email your invoices, userhrvisionstaffing.
When you're unable to email invoices in QuickBooks Online, it could be because of the following:
Email is incorrect.
No internet connection.
Please make sure to check the customer's email address. If it's correct and you have a strong internet connection, let's try refreshing your browser by pressing F5 on your keyboard. Then, email the invoice again.
If you're getting the same result, we can do some basic troubleshooting steps. To do that, sign in to your QuickBooks Online account using the incognito or private browser. This mode will not save the cache and cookies.
You can use these keyboard shortcuts:
Google Chrome: Ctrl + Shift + N
Mozilla Firefox: Ctrl + Shift + P
Safari: Command + Option + P
Open the invoice and try sending it. If you're able to email the invoice, go back to your regular browser and clear its cache. Clearing cache helps refresh your browser settings. Restart your browser afterwards.