Invoice Creation email not sent to single user?

[yabdab]

I have things set up to send out emails when invoices are created. All invoices are generated the same day. Most of my clients get the email without any problems. But I have one that the email is not sent. I check this clients past emails and sure enough, it does not send the email. Now it sends the overdue notices, but not the invoice created email.

 

Any ideas what I am missing here?

 

Thanks.