You cannot legally demand the mail not originally addressed to you and can put you into legal hurdle.
depends
Yes it is illegal to steal other peoples coupon's out of the mail. The mail is delivered to you and addressed to you if anyone other than the person that is suppose to receive the mail gets it without permissions it is stealing.
If it was personal mail - addressed to you - and they failed to forward it to you - yes. If it was business correspondence simply addressed to you (by someone thinking you still worked there), no.
Yes, it is illegal for a parent to open mail addressed to their teenage child without permission. Mail tampering is a federal offense under the United States Code.
Yes, It is a federal crime if there is no permission.
Not if you did it mistakenly and without a criminal intent. Take your first opportunity to return it to the carrier or the post office though.
Yes, any mail that is delivered to your mailbox is legally yours. The United States Postal Service considers the mailbox to be an extension of your property, making the mail legally yours once it is delivered. However, it is illegal to open or tamper with mail that is not addressed to you.
Unless the envelope is marked CONFIDENTIAL or PERSONAL they have a right to open any mail addressed to the business location.
While you may not OPEN mail addressed to someone else without their permission, it is perfectly lawful to use ANY public mailbox you wish, there is no problem.
I don't know about minors and parents, but see Related Link below.
It belongs to the person to whom it is addressed.
In most places it would theoretically be illegal for her to do so without his permission. However, in practice, it's unlikely that she'd be prosecuted for doing so; she'd normally be considered to be acting as his agent (much as a secretary might open email addressed to her boss).