Existing residential mailbox laws state that only authorized letter carriers may insert mail into a residential mailbox. A penalty will be imposed for anyone who is not a letter carrier and is inserting mail in the residential mailbox. It is a federal offense for tampering with the mail and a fine or possibly jail time can be the punishment for the offense. Generally, resident mailboxes are for mail use only.
Not unless it was, perhaps, mis-delivered to your box instead, and you are doing your neighbor a favor by doing so. US Postal Regulations prohibit the placing of anything into a mailbox EXCEPT those items sent through, and delivered by, the US Postal Serivce. An exception to this would be, if the "mailbox" being referred to is actually a mail SLOT cut into the door or wall through which deliveries are made directly into the interior of a business or dwelling.
If a person writes a letter or a note to their neighbor and places it into their mailbox without placing postage on it, this is definitely illegal.
If they are writing a letter to a third party and properly stamp the letter, technically they can place the outgoing letter into any U.S. Mailbox. Most people are not crass enough to do this, however.
It is also illegal to deliver improperly delivered mail to the correct person's mailbox. It should be marked "Not at this address" and placed back in your own mailbox. Any other use constitutes mail tampering.
Put it back in the mailbox and send it.
US postal regulations state nothing but US mail can be put into a mailbox
In a mailbox.
the letter will be thrown away - doh
Nothing is to be put in an approved mailbox that has not been delivered by the USPS. But there is nothing wrong with you handing a letter to or slipping one under the door of your neighbors house.
Write him a letter and put it in the mailbox.
That depends on where you put it. A mailbox could be anywhere.
yes put the flag up so he knows its there
Yes, anything under 13 ounces can be put in the mailbox
Eventually it will come back to you stamped with a note saying postage missing.
no it is illegal t open someone else's mailbox
It is not legal to place flyers between the flag and the mailbox, as this can interfere with mail delivery and constitutes tampering with the mail. It is best to avoid placing any items in this space that could obstruct or misdirect mail delivery.