Long story short, I am getting Dutch language spam from a group; it has been going on for years, and they send several of them daily. They got my e-mail when I lived in the Netherlands and imagine that their "business" is very profitable and I'm just lucky to not speak Dutch and therefore it was easy to ignore them this long.
Still, I finally reported some of their domains to web.com, the registrar they use, whose abuse department replied:
Although the domain name is registered through Register.com/Network Solutions/Web.com, the e-mail itself, which is separate from the domain name registration, is hosted elsewhere and we have no control over the website, e-mail or its content. Any issues regarding the content of the website or e-mail will need to be addressed directly to the owner of the site or to the e-mail-hosting provider who should be in a position to assist you with your concerns. To determine the mail-hosting provider you can use a publicly available tool such as http:www.mxtoolbox.com this tool will provide you with the e-mail hosting provider of the domain name, which can then be compared to the ARIN.net (http://www.arin.net) IP allocation database. This will give you the relevant information for the true e-mail hosting provider.
Now the problem is that I could not properly locate the hosting providers for their domains - peabolin.com, suraccess.com, compun.org, etc. - with those tools and need your help with doing that (also for their future domains as I'm sure they will keep trying).
Update: let me copy here the response from another registrar (namecheap.com) as well which cared much more than web.com about my complaint, as an encouragement for others to take action:
... it seems the domain name is blacklisted by SURBL. Since we consider SURBL to be a trusted organization, we opened a case regarding the domain name.
(and 2 business days later:)
This is to inform you that the potyxc.men domain was suspended. It is now pointed to non-resolving nameservers and will be null routed once the propagation is over. The domain is locked for modification in our system.