[April 13, 2018 – UPDATE]

We initially thought they are false positives, but every manual check we’ve done has been verified on their website as well, and confirmed not to be a false positive.

It looks like they are just blacklisting and delisting entire blocks within short intervals of time (same day), for some reason.

This could be due to human error or some kind of malfunction on their side, unfortunately completely out of our hands.

If you wish to disable checking this RBL for your account, you can do so as described in our documentation:  

We’ll continue to monitor the situation further, as it develops.

[April 8, 2018]

SenderScore (bl.score.senderscore.com) has started issuing a lot of false positives.

We are actively monitoring the situation as it develops.