Cart not generating email for a sale

Previously sales have always generated an email from the system but today a sale happened and no email was generated. I was notified about the sale from PayPal, which is the only way I knew about it. Usually I get the PayPal email and one from the TTG Cart system.

My contact form still works if someone sends an email that way.

Does anyone know what may be the problem and how to correct it?
Thanks!
~Scott

spam/junk folder?

Hi Rod! No, I checked those thoroughly. Sorry I should have mentioned that.

Is the order still showing up in backlight>Cart>Orders?

Yes.

Well, I just created a 100% discount code and tried making a purchase myself and it worked and sent me an email just fine. Who knows what happened with that particular customer and order yesterday. Thanks to Rod and all that took a look at this issue.