No, it is illegal to put mail in someone else's mailbox unless you are a postal worker or have permission from the mailbox owner.
Not legally.
No, you can only put mail in mailboxes that belong to the postal service or have permission to receive mail.
Yes, you can put letters in mailboxes for delivery by the postal service.
No. Mailboxes are protected property. Everything placed into a mailbox should be stamped and posted.
depends on whose mailbox your doing it too and plus a lot of ppl do that have you ever got pizza flyers
yes because you are invading their privacy. if you have some of their mail and the mail person put it in your mailbox instead then wait till they get home and go tell them, don't put it in yourself.
If you live in a neighborhood, put fliers in peoples mailboxes letting them know you are intrested!!
You cannot legally demand the mail not originally addressed to you and can put you into legal hurdle.
No, it is illegal to put something in someone's mailbox without their permission, as it is considered tampering with the mail.
put posters in your neighbors mailboxes that you know have kids.
A person that owns there own rural mailbox can leave personal things in the mailbox that are not going to be mailed, but they should be kept separate from regular mail. The personal items should be put inside a coffee can or something similar so that the mailman does not think they are mail.
The USPS's website (PDF) states: "Except under 2.11 [dealing with newspaper boxes attached to mailboxes], the receptacles described in 1.1 may be used only for matter bearing postage. Other than as permitted by 2.10 or 2.11, no part of a mail receptacle may be used to deliver any matter not bearing postage, including items or matter placed upon, supported by, attached to, hung from, or inserted into a mail receptacle." Note that "door slots and nonlockable bins or troughs used with apartment house mailboxes" are excluded from this prohibition, and can be loaded up with as many flyers as they can hold. The USPS's website (PDF) states: "Except under 2.11 [dealing with newspaper boxes attached to mailboxes], the receptacles described in 1.1 may be used only for matter bearing postage. Other than as permitted by 2.10 or 2.11, no part of a mail receptacle may be used to deliver any matter not bearing postage, including items or matter placed upon, supported by, attached to, hung from, or inserted into a mail receptacle." Note that "door slots and nonlockable bins or troughs used with apartment house mailboxes" are excluded from this prohibition, and can be loaded up with as many flyers as they can hold.