We started to receive reports of Blackholes.us blocking all incoming emails.
This DNS Blacklist does not operate for some time now: the IP address space that they used for name servers now belongs to another, unrelated entity. Since many email administrators forgot to disable Blackholes.us in their anti-spam applications, the new owner continued to receive a huge amount of DNS queries. Due to this, they decided to return a 127.0.0.2 response for all queries, which means if you have Blackholes.us enabled, all incoming email will be rejected. (Similar thing happened to ORDB a while back)
To solve this, you should disable and/or remove Blackholes.us from your DNS Blacklist definition set (ORF Administration Tool: Configuration / Tests / DNS Blacklists). Finally, save your configuration to apply the configuration changes by pressing Ctrl + S. (Pre-4.3 versions also require a restart of the ORF Service: if you have such version, press Ctrl + U instead).
The recommended DNS Blacklists are listed in our best practices guide. We would recommend updating your whole definition set, as Spamhaus has also released an update recently. To wipe out Blackholes.us and to update Spamhaus at once, follow these steps.