This blocklist is no longer operational. DNS queries return NXDOMAIN. Remove from MTA configurations to avoid query timeouts.
What it is
MAPS operated several influential early blocklists including the RBL (Realtime Blackhole List), RSS, and DUL. These were among the first commercial-grade blocklists. After Trend Micro acquired MAPS, the free public DNSBL service was discontinued and moved to a paid enterprise subscription model unavailable to most mail operators.
Ownership history
How it affects SMTP delivery
The legacy MAPS free zones are no longer operational. No impact on email deliverability for general use.
What causes a listing
N/A, defunct for public use.
How to get removed
No removal necessary for the free zones. Enterprise subscribers should contact Trend Micro support.
For the full reference catalog, see the email blocklist directory.
Delisting process in detail
The Konstant Blocklist (also known as bl.konstant.no) is a Norwegian-operated blocklist targeting spam sources observed by Konstant Consulting’s mail infrastructure. Delisting is handled through the operator’s contact form. Because Konstant is a small volunteer-operated blocklist, response times vary but are typically within 24-72 hours for well-documented requests. Automatic decay occurs when the observed spam pattern stops, usually within 7-14 days.
Prevention practices
Konstant prevention follows standard anti-abuse fundamentals: authenticated sending (SPF, DKIM, DMARC), disciplined list hygiene (double opt-in, prompt bounce suppression), and complaint monitoring. Because Konstant is a smaller regional blocklist, its impact is limited to receivers that specifically query it. Enterprise senders reaching Norwegian recipients should monitor Konstant alongside Nordspam and Spamhaus for comprehensive Nordic deliverability coverage.
Common listing causes
Konstant listings correlate with actual observed spam sending. Common patterns include purchased lists containing harvested addresses that hit Konstant honeypots, compromised shared-hosting accounts blasting spam through the sending infrastructure, and coordinated spam campaigns targeting Norwegian recipients. Because Konstant operates a smaller honeypot network than major blocklists, listings often indicate specific abuse rather than broad reputation issues.
Related blocklists
Regional European blocklists overlap in coverage but each operates independently. Konstant, Nordspam, Nether, and NIX Spam collectively cover the European regional mail community with different operator focuses. Enterprise reputation monitoring combines these regional lists with Spamhaus, Barracuda, and other global blocklists for comprehensive coverage. For senders primarily reaching non-European recipients, Konstant impact is minimal; for European operations, it matters alongside other regional lists.
About the Author
Alaa · LinkedIn
Email infrastructure specialist with 8+ years of hands-on experience in SMTP, deliverability, and email verification. I’ve configured and troubleshot mail systems across Postfix, Exchange, and cloud relays, managed IP reputation and warmup campaigns, and built verification pipelines processing millions of addresses. My work spans DNS authentication (SPF, DKIM, DMARC, BIMI), bounce handling, blocklist monitoring, and compliance frameworks including CAN-SPAM and GDPR. I write every article on SMTPedia to give email professionals, developers, and marketers the accurate, RFC-grounded reference they need.
About SMTPedia
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