I have another step between 1 and 2: send a mail to the abuse contact of their AS. You can do it either manually, or with a tool like https://www.spamcop.net/ h

I have another step between 1 and 2: send a mail to the abuse contact of their AS. You can do it either manually, or with a tool like https://www.spamcop.net/ https://www.spamcop.net/ . Sometimes it works (but rarely).