I agree that it is not "simple" if you take that to mean "permanent". Every move you make only encourages them to find a different route, I am afraid

There are a number of good "antispam" type sites around and you have to constantly monitor them to stay up to date with the latest threats.

There are two major problems with any attempts at "vigilante" action in my opinion:

1. It is probably illegal under your local legislation.
2. The "target" may well be a "victim" themselves?

This problem will remain whilst:

1. The Russian and Chinese governments continue to ignore the issue.
2. People continue to run insecure systems.

Unfortunately, that is a fact of life

Cheers