After looking at NANAS hits for FPs, in particular the reporting parties and the destination addresses, I have a theory about some of the FPs. I think some anti-spam zealots may be deliberately subscribing spam traps, either their own or third parties' like Outblaze, to sites with open subscriptions. If so, they're probably doing it to draw attention to the fact that the sites have unconfirmed subscriptions.
Or they could be cracker/spammer types trying to use them to poison the spamtrap feeds and therefore diminish the usefulness of data from them. This type of poisoning is a distinct possibility since it would appear that the "spams" (usually subscription newsletters) do appear to come from those sites or senders.
I think we should consider the possibilities that either type of people (or even bots) could be adding otherwise legitimate sites to traps this way. (It would be trivially easy to write a spider to subscribe spamtrap or their own address to open subscription sites, and given some of the repeated reporters in NANAS, someone may have done that.)
Whatever their reasons, we should not fall into this trap and list otherwise legitimate sites just because they have open subscriptions. Doing so probably diminishes the usefulness of SURBLs by increasing false positives.
Comments,
Jeff C. -- "If it appears in hams, then don't list it."