I am puzzled as to why I have instances where payment thank you emails fail to send out. I get an error message when trying to email thank yous to customers where the system claims "no email is associated with this customer" yet I ensured that the client had an email tied to him/her before accepting the payment through the system.

What is the key to having these emails send out without a problem? Am I doing something wrong? Does the checkmark have to be selected where the customer should be emailed the invoice right during invoice creation, in order to use payment Thank You at the end?

I am curious how I can get this working correctly. Thank you.