I remember hearing about DNS real-time blackhole lists years ago, and I think it was in a news magazine. Which probably means that the wannabe journalist who wrote the article didn’t really understand what it was. Which in turn, probably doesn’t say much for my understanding of it.
On the other hand, it’s fairly obvious after using rblcheck.
For a program last updated 10 years ago, rblcheck shows no signs of quitting. This clever little program runs an address past DNS-based IP blacklist databases, and shows if it’s “filtered” or not.
If rblcheck says something is “filtered,” then you could conceivably use that as criteria for blocking spam. Conversely, “not filtered” is probably safe.
I wouldn’t dare suggest how you run your e-mail system, and I hardly have the expertise or credentials to make an endorsement here.
On the other hand, this seems like a simple and straightforward first step toward cutting back on garbage communications. You know who you are. 👿