Adding variables such as Invoice Date and Invoice Due Date in invoice email reminders is currently unavailable in QuickBooks Online (QBO), paul82.

Please know that we value user insights on how to improve existing features or add new ones. With that, I encourage you to send feedback to our product engineers so they can review your suggestion and consider it for future updates. Here’s how:

1. Select the Gear icon, then choose Feedback.
2. Type in your product suggestions.
3. Select Next to submit.

As a workaround, until QuickBooks supports invoice date and invoice due variables in email templates, you can manually add this information in the email body of your invoice reminders.

You can also change the online delivery format to Plain text in the Account and settings. This allows your customers to see complete invoice details including Invoice No., Date, Due Date, Terms, and Amount Due when they receive your invoice reminder email.

I've included a screenshot below for reference:

To do this:

1. Go to the Gear icon, then click Account and settings.
   
   
2. Hit the Sales tab and look for the Online delivery.
   
   
3. Click on the pencil icon, then choose Plain text under the dropdown arrow.
4. Once finished, click Save and Done.
   
   

Once settled, you can check out this article on managing your customer payments. It covers receiving payments for invoices: Receive invoice payment.

The Community is always here if you need anything else.