Why are my invoices going to customers spam folders

Unrecognized sender will end up in your customers' spam folders, @Ljpequestrian. 

The spam folder contains emails that your customer's email service provider has recognized as possibly unsafe. To ensure that important emails are not mistakenly classified as spam. Advise your customers to mark emails from quickbooks@notification.intuit.com as "Not Spam" or "Not Junk" and add this address to their contacts. This helps their email provider recognize @intuit.com as a trusted sender.

Feel free to check this resource: Receive important email messages from Intuit. This guide will outline Intuit's service and approved email addresses. 

Speaking of invoices, you might find the article Record Invoice Payments helpful. This guide will help you keep track of the money you receive from clients. By recording these payments correctly, you can see how money comes in and goes out of your business.

Let us know if you need anything else.