What it is
0SPAM maintains both an IP-based RBL and a complementary standard list. The lists are populated from spam trap hits and community-submitted spam reports. 0SPAM operates with a focus on low false positives and provides a public lookup tool.
How it affects SMTP delivery
0SPAM is used as a spam scoring input in SpamAssassin installations. Limited deployment compared to major lists.
What causes a listing
Listings occur from spam trap hits or community spam reports.
How to get removed
Use the 0SPAM portal at www.0spam.org for lookup and removal requests.
For the full reference catalog, see the email blocklist directory.
Delisting process in detail
The 0Spam blocklist (bl.0spam.org) targets observed spam sources. Delisting is handled through 0spam.org’s portal. Automatic decay applies when the observed abuse pattern stops, typically within 7-14 days. Manual delisting requests are typically resolved within 24-72 hours for well-documented cases. 0Spam operates a mid-scale honeypot network and provides regional coverage for smaller mail providers.
Prevention practices
0Spam prevention follows standard anti-abuse fundamentals: authenticated sending, list hygiene, complaint monitoring. Because 0Spam operates a smaller honeypot network than major blocklists, listings typically reflect specific abuse patterns rather than broad reputation issues. Gradual IP warmup and confirmed opt-in remain the primary defenses. Monitor 0Spam alongside major public blocklists for comprehensive coverage.
Common listing causes
0Spam listings correlate with observed spam sending. Common causes include purchased lists that hit 0Spam honeypots, compromised shared-hosting accounts sending spam through the listed IP, and coordinated spam campaigns. Because 0Spam operates a smaller network than major blocklists, listings often provide early-warning of patterns that would eventually trigger broader consensus lists as well.
Related blocklists
0Spam operates alongside other mid-scale blocklists that provide regional or specialty coverage. Enterprise reputation monitoring combines 0Spam with major blocklists (Spamhaus, Barracuda, SpamCop) for comprehensive coverage. Because smaller blocklists sometimes react faster to specific patterns than consensus lists, they can serve as early-warning signals for reputation degradation before it produces broader listings.
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
SMTPedia is an independent email industry reference covering SMTP, IMAP, POP3, email deliverability, marketing platforms, DNS authentication, and email verification. Every article is researched from official provider documentation, IETF RFCs, and industry best practices. Settings and configurations are verified quarterly.
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