A man was in his front yard mowing grass when…

A man was in his front yard mowing grass when his neighbour, came out of the house and went straight to the mailbox. He opened it, looked inside, slammed it shut, and stormed back into his house.
A little later he came out of his house again, looking nervous, went to the mailbox, again opened it, and slammed it shut again. Angrily, back into the house he went.
As the man was getting ready to edge the lawn, where he came again, looking very heated up. He marched to the mailbox, opened it and then slammed it shut harder than ever.
Puzzled by his actions, the man asked him, “Is something wrong?”
To which the ferocious neighbour replied, “There certainly is! My stupid computer keeps telling me I have mail!”