.@ Tony Finch – blog

We use the JANET subscription to the MAPS RBL+. It is a frequent source of false positives which causes a great deal of irritation.

Sadly I can't easily ditch the RBL+ since using both it and ZEN adds 20-25% to our block rate compared to either alone, so performance would suffer horribly. Also, I don't want to get into the game of maintaining my own blacklist and/or whitelist - a time sink I do not need.