Here in Australia the Freedom of religion right ceases at the front gate and, if the occupant of a property puts up a "do not knock" sign "no hawkers" or, "no trespassers", your right of access to the property has been denied. If you knock, you break the law. If a no junk mail sign is on the mailbox, no literature is to be placed therein. Any mail you try to place in the mailbox must be addressed to the person directly and not simply "to the householder"
Most jw's that I know respect any occupants' request in this matter. There are of course the uber zealous and illiterate ones, as there are in society generally.
I must say, there is an increase in signs stating jws directly as not being welcome.
The best one I've heard of is where the occupants sign states that "before you knock. be aware that a charge rate of au$50.00 per minute will be made for any religious discussion. If you agree with this then feel free to knock". I kid you not its a ripper. apparently a few of them have been spotted.
jtg