Reciting article:
Book2, Unit 24: Post office
Mail boxes are strictly used only to send and receive mail. You are not allowed to put anything besides letters inside a mailbox, even if it's the box in front of your house.
Most mailboxes in front of people's house have a red flag on the side. That's used to tell the letter carrier you have a letter to deliver. Place a letter in the box and raise the flag. After te letter carrier has taken the letter, he will lower the flag.
Large blue mailboxes are found on city streets across America. Mail pick-up times are written on the inside of the box's lid.
To make sure the person or organization you write a letter to will reply, include SASE (Self-Addressed Stamped Envelope) Your address is written on the envelope, and enough postage stamps to mail the letter are placed on the envelope.
Unwanted Internet mail is called "spam". Most e-mail programs allow you to block letters sent from spammers (people who send you spam)
