I can see how the ability to include three email addresses in your invoice would meet your business needs, jjreichardt. I'm here to share some insight.

As of now, we're unable to add multiple emails in QuickBooks Online. I'd recommend sending a feature request directly to our Product Development team. This helps us improve your experience with the program. 

Here's how:

1. Go to the Gear menu and then select Feedback.
2. Type in your feature request in the description box.
3. Once done, click on Next.
   

Also, you can track feature requests through the Customer Feedback for QuickBooks Online website.

Additionally, I've included these articles that'll help you send reminders to your customers once their invoices are soon to be due. This way, you'll be able to ensure you're paid on time:

• Send invoice reminders automatically or manually
• Create recurring transactions in QuickBooks Online

Please get back to me if you have questions about managing QuickBooks, jjreichardt. I want to make sure you're taken care of. It's always my priority to help.