What it is
SPFBL is an open-source blocklist project that extends traditional DNSBL functionality with SPF (Sender Policy Framework) validation. It lists sending IPs that fail SPF checks for their envelope sender domains, in addition to IPs identified as spam sources through SPFBL's participating server network.
How it affects SMTP delivery
MTAs querying SPFBL at connection time use the result to reject connections from listed IPs. The list is primarily deployed in Brazil and Latin America but is accessible to any MTA globally.
What causes a listing
Listings occur from SPF check failures (your IP is not in the SPF record of the domain you are sending from) or from spam trap hits on the SPFBL network.
How to get removed
Use the SPFBL client tool or the web portal at spfbl.net to check your listing and request removal. Removal requires demonstrating valid SPF configuration and clean sending behaviour.
For the full reference catalog, see the email blocklist directory.
Delisting process in detail
SPFBL is a Brazilian-operated blocklist that combines SPF authentication verification with reputation scoring. Delisting is handled through spfbl.net’s portal and typically requires demonstrating that SPF authentication is correctly configured for the sending domain. Automatic delisting occurs when the observed abuse pattern stops and SPF alignment is verified. SPFBL is unusual in that it specifically penalizes IPs that send with broken or missing SPF authentication, treating that as a spam signal in itself.
Prevention practices
SPFBL prevention starts with proper SPF configuration: publish a valid SPF record that lists all authorized sending IPs, ends with -all (strict) or ~all (soft-fail), and stays within the 10-DNS-lookup limit imposed by the SPF specification. Broken SPF records (syntax errors, too many lookups, missing all mechanism) are treated as spam signals by SPFBL. Combine SPF with DKIM signing and DMARC policy for strongest authentication. Test SPF configuration at kitterman.com or mail-tester.com before deploying changes.
Common listing causes
SPFBL listings usually stem from one of three patterns: missing or broken SPF records on the sending domain, actual observed spam sending, or SPF records that exceed the 10-DNS-lookup limit (a common issue for senders using many third-party ESPs, since each ESP typically requires its own SPF include). The 10-lookup limit causes SPF to fail even when the record is syntactically correct, which SPFBL treats as unauthenticated sending. SPF flattening tools can reduce the lookup count.
Related blocklists
SPFBL is one of few blocklists that specifically evaluates authentication. Most general blocklists (Spamhaus, SURBL, SpamCop) evaluate spam signals without specifically checking SPF, though authentication status often feeds into their reputation scoring indirectly. Authentication-focused reputation systems (DMARC Reject rate at Gmail, Outlook, Yahoo Postmaster Tools) provide comparable signal. Enterprise senders reaching Brazilian and Latin American recipients should monitor SPFBL specifically because of its regional deployment.
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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