I've had /23s and /22s listed as dynamic incorrectly, and anti-spam organizations wouldn't take them off even when they were either SWIPd through to my company, or were in my ASN.
Getting off the lists is an enormous pain in the ass. They make absurd demands, like changing the rDNS on every single IP in the block to contain the word static.... as though breaking rDNS is a good idea.
Argh. Well that's pretty indefensible. There must be some reason, though - you probably had the bad luck to take over a block that had previously been blacklisted.
That "static" thing is just stupid. God I wish ISPs would just standardise on putting "dyn" into the rDNS of their dynamic IPs though. That would solve so many problems.
you probably had the bad luck to take over a block that had previously been blacklisted.
That's exactly what happened. It was apparently dial-up space many years ago.
I say many, because the space in question has been under my control since 2005, and it's STILL on the dynamic ip list, despite a roughly annual attempt to get de-listed.