IP address blacklists are normally unreliable and a poor approach to controlling whatever it is people are trying to control. But administrators definitely use them.
Recently, some forums are not allowing me to register because they claim I’m a spammer. The administrator on one of them emailed me that my IP address is on some kind of blacklist. Now, I’ve checked my IP address on many blacklists and I was all green and clean so what’s the matter here? Should I or could I change my IP address? Is there any way to locate that blacklist and get me taken off?