> That tactic is now illegal, so they only send out to customers who has subscribed to it and the letter must have instructions on how to unsubscripted.
Reputable people may do that but my mail server is still getting 1000s of spams a day.
Correct, and this is the business concept behind technology that is intended to block spam while still permitting the reputable mail passage to the user. One of the commonly argued reason to use gmail has been its spam blocking features.
