Email blocklist · DNSBL · Entire ASNs
THU · 11 JUN 2026
UCEPROTECT Level 3
About
UCEPROTECT escalation level 3. Whole-ASN listing; the most aggressive of the three. Rarely used as a hard block; some operators use it as a scoring input only.
Listing criteria
Listing applied to entire ASNs based on aggregate L1/L2 activity. Most operators do not use L3 as a hard block; the false-positive rate is high.
How to query
For an IP address 1.2.3.4, query reversed-octets-dot-zone:
dig +short 4.3.2.1.dnsbl-3.uceprotect.netA returned IP (such as 127.0.0.2) means listed. Each blocklist has its own set of return codes meaning different things; the operator's documentation explains theirs.