Al posted an analysis on DNSBL Resource about the effectiveness of the FiveTen blacklist.
Analysis of the raw data suggests to me that Fiveten’s poor (high) false positive rates is primarily due to Fiveten’s listing of “bulk mailers that don’t require closed loop confirmation opt-in from all their customers.” As a result, Fiveten has thousands of senders listed that have never send spam, specifically because they choose not to utilize double opt-in. This means that Fiveten is effectively a tool that blocks “things the maintainer doesn’t like,” which is a wholly different criteria than blocking spam. Against my own data, it appears that there is no direct correlation between spam and the blacklist maintainer’s choices for listing criteria.
I’ve not been worrying much about FiveTen listings with my clients over the years. Analysis of delivery logs shows that FiveTen is not widely used by large receiver sites and the number of emails rejected related to a FiveTen listing is relatively low.