A man is found murdered on a Sunday morning. His wife calls the police, who question the wife and the staff, and are given the following alibis:

The wife says she was sleeping,

The butler was cleaning the closet,

The gardener was picking the vegetables,

The maid was getting the mail

and the cook was preparing breakfast.

Immediately, the police arrest the murderer.

Who did it and how did the police know?

Answer:

The maid. There is no mail on Sundays.

Taken from: 9GAG