"Truncate" is an rfc5782 compliant DNSBL.
You can access this DNSBL via the zone truncate.gbudb.net.
A result of 127.0.0.2 indicates that the IPv4 address in question produces exclusively email containing spam, scams, viruses, or other malware based on statistics in the global GBUdb network. The parameters used to select IPs for this list are so strict that most systems should be able to safely reject SMTP connections from IPs found on this list.
Maintenance of this list is completely automated and there are no provisions for the manual addition or removal of entries.