Blonde Mail Call

A man was mowing his front yard when his attractive, blonde, female neighbor came out of the house and went straight to her mailbox. She opened the mailbox, looked inside, slammed it shut, and stormed back into her house. A little later, she came out of her house again, went to the mailbox, again opened it, and again slammed it shut. Angrily back into the house she went.
As the man was getting ready to edge the lawn, the blonde came out again. She marched to the mailbox, opened it and then slammed it closed harder than ever.
Puzzled by her actions, the man asked her, "Is something wrong?"
She replied, "There certainly is! My stupid computer keeps telling me I have mail!"