Why do I have to enter a customer email in order to be able to post invoices?

Hi ediedeyoung-gmai,

Welcome to Community!  QuickBooks Online is a dynamic program with the features you need to complete your daily bookkeeping tasks with confidence.  Once you've set up your customer list, you can create and send invoices effortlessly.  I'd be happy to provide some insight here!

Not all customers will have an email address, or you may not have that information.  This is not a required field.  However, if you hit Save and Send, when your invoice has been created, a copy will be sent to your customer's email address.  If there is no email address for the customer, you'll see a prompt indicating that the information is missing.  In your situation, I suggest selecting Save, Save and close, or Save and new, when creating your invoices.  

If you have any other questions, please don't hesitate to reach out again.  We are always glad to help!