What does it mean when an email is returned saying the e-mail address is restricted?

Question

Below is the top part of the text of the message I was sent by [e-mail] . I sent this person an e-mail a couple days ago with no prob....


Hi. This is the qmail-send program at yahoo.com.
I'm afraid I wasn't able to deliver your message to the following addresses.
This is a permanent error; I've given up. Sorry it didn't work out.

does not like recipient.
Remote host said: 555 mailbox *******@*******.com ( I blocked out the address)is restricted

Answer 1

its either blocked or not a proper e-mail address

Answer 2

might be a banned email address from yahoo. obviously you wont be able to send again as it is a 'permanent error'

Answer 3

you can get e-mail to not allow messages from anyone but your contacts