Thank you for taking the initiative to troubleshoot, mpmonteith. Let's explore additional solutions to ensure you can send invoices successfully.
To begin, please remove and then re-add your email address to refresh the connection. Here's how:
- Go to the Gear icon, then select Account and settings.
- In the Company section, remove and re-enter your email under Contact info.
- Click Save, then press Done.

After that, conduct a test transaction to check if it works. If it doesn’t, I recommend contacting our Live Support team. They can review your account in detail and perform screen-sharing in a secure environment to help identify and resolve the issue.
Alternatively, you can save the invoice as a PDF and send it externally via your company email, outside of QuickBooks.
When this gets fixed, you can proceed with recording the payment, please refer to this article for comprehensive guidance: Record invoice payments in QuickBooks Online.
If you need further assistance handling your invoices in QuickBooks Online, please let us know by adding your inquiries below. My team and I are always available to help in any way we can.