Summary
Spamhaus blocks RBL queries for various reasons, including excessive querying, open resolvers, generic rDNS, OVHcloud usage, and association with spam or malicious activity. Solutions involve using the Data Query Service (DQS), ensuring non-generic rDNS, preventing spam origination, utilizing static IPs, implementing SPF, DKIM, and DMARC, monitoring IP reputation, using caching, following best practices, and addressing underlying issues leading to blacklisting. Shared IP users should consider dedicated IPs or reputable ESPs. Understanding Spamhaus's specific lists (SBL, ZEN) is crucial.
Key findings
- Excessive Querying: Excessive RBL querying without caching or respecting TTL can cause blocking; use DQS for high-volume lookups.
- Open Resolvers & rDNS: Using open resolvers or having generic rDNS can lead to blocking; ensure valid, non-generic rDNS.
- OVHcloud Usage: If querying via OVHcloud's DNS, migrate to the free DQS.
- Spam Origination: Being blocked often indicates spam origination; identify and stop the source.
- Dynamic IPs: Spamhaus often blocks dynamic/residential IPs; use static IPs.
- Shared IP Issues: Shared IP reputation is affected by other users; consider a dedicated IP or ESP.
- Authentication Protocols: Lack of SPF, DKIM, DMARC increases blacklisting risk; implement these.
- Spamhaus Lists: Being on SBL or ZEN indicates spam or malicious activity; address the cause.
Key considerations
- Caching: Implement caching to reduce RBL query frequency.
- Identify the Cause: Determine the specific reason for the blocking/listing.
- Take Corrective Action: Clean compromised servers, secure accounts, and stop spamming activity.
- Monitor Reputation: Use Sender Score or similar tools to monitor your IP reputation.
- Follow Delisting Process: Understand and follow Spamhaus's delisting process after fixing the issue.
- Best Practices: Adhere to email sending best practices (clean lists, consent, relevant content).
Spamhaus
0Spam
Cisco
NoSolicitado
URIBL
abuse.ro
ALPHANET
Anonmails
Ascams
BLOCKEDSERVERS
Calivent Networks
EFnet
JustSpam
Kempt.net
NordSpam
RV-SOFT Technology
Scientific Spam
Spamikaze
SpamRATS
SPFBL
Suomispam
System 5 Hosting
Team Cymru
Validity
www.blocklist.de Fail2Ban-Reporting Service
ZapBL
2stepback.dk
Fayntic Services
ORB UK
technoirc.org
TechTheftSpamhaus0SpamCiscoNoSolicitadoURIBLabuse.roALPHANETAnonmailsAscamsBLOCKEDSERVERSCalivent NetworksEFnetJustSpamKempt.netNordSpamRV-SOFT TechnologyScientific SpamSpamikazeSpamRATSSPFBLSuomispamSystem 5 HostingTeam CymruValiditywww.blocklist.de Fail2Ban-Reporting ServiceZapBL2stepback.dkFayntic ServicesORB UKtechnoirc.orgTechTheftSpamhaus0SpamCiscoNoSolicitadoURIBLabuse.roALPHANETAnonmailsAscamsBLOCKEDSERVERSCalivent NetworksEFnetJustSpamKempt.netNordSpamRV-SOFT TechnologyScientific SpamSpamikazeSpamRATSSPFBLSuomispamSystem 5 HostingTeam CymruValiditywww.blocklist.de Fail2Ban-Reporting ServiceZapBL2stepback.dkFayntic ServicesORB UKtechnoirc.orgTechTheftSpamhaus0SpamCiscoNoSolicitadoURIBLabuse.roALPHANETAnonmailsAscamsBLOCKEDSERVERSCalivent NetworksEFnetJustSpamKempt.netNordSpamRV-SOFT TechnologyScientific SpamSpamikazeSpamRATSSPFBLSuomispamSystem 5 HostingTeam CymruValiditywww.blocklist.de Fail2Ban-Reporting ServiceZapBL2stepback.dkFayntic ServicesORB UKtechnoirc.orgTechTheftSpamhaus0SpamCiscoNoSolicitadoURIBLabuse.roALPHANETAnonmailsAscamsBLOCKEDSERVERSCalivent NetworksEFnetJustSpamKempt.netNordSpamRV-SOFT TechnologyScientific SpamSpamikazeSpamRATSSPFBLSuomispamSystem 5 HostingTeam CymruValiditywww.blocklist.de Fail2Ban-Reporting ServiceZapBL2stepback.dkFayntic ServicesORB UKtechnoirc.orgTechTheftWhat email marketers say
12 marketer opinions
Spamhaus blocks RBL queries for various reasons, including excessive querying, using open resolvers, generic rDNS, or being associated with OVHcloud's DNS. Resolving this involves switching to Spamhaus's Data Query Service (DQS), ensuring a non-generic rDNS, stopping spam origination (if any), using static IPs (avoiding dynamic ones), implementing proper email authentication (SPF, DKIM, DMARC), monitoring IP reputation (Sender Score), and adhering to email sending best practices (clean lists, consent). Shared IP users might consider a dedicated IP or reputable ESP.
Key opinions
- Query Limits: Exceeding query limits or using open resolvers can lead to blocking; consider using DQS.
- rDNS Issues: Generic rDNS can cause blocking; ensure a non-generic rDNS record.
- OVHcloud Specifics: If using OVHcloud, migrate to the free DQS.
- Spam Source: Being blocked often signals spam origination; identify and stop the source.
- IP Type: Dynamic or residential IPs are often blocked; use static IPs.
- Shared IP Risks: Shared IPs can be affected by other users' actions; consider a dedicated IP.
- Authentication: Lack of SPF, DKIM, and DMARC increases blacklisting risk; implement these protocols.
Key considerations
- Identify Cause: Determine the specific reason for the Spamhaus listing to take targeted action.
- Clean Server: If compromised, thoroughly clean and secure the server.
- Monitor Reputation: Regularly check your Sender Score or similar metrics to proactively address issues.
- Follow Best Practices: Adhere to email sending best practices to maintain a good sender reputation.
- Delisting Process: Understand and follow Spamhaus's delisting process after addressing the cause.
Marketer view
Email marketer from DigitalOcean explains that ensuring proper DNS records (SPF, DKIM, DMARC) is crucial for email deliverability and avoiding blacklists. Make sure your DNS records are correctly configured and validated.
6 Jun 2025 - DigitalOcean
Marketer view
Marketer from Email Geeks shares a link to Spamhaus documentation stating that if you query Spamhaus' DNSBLs via OVHcloud's DNS, you should move to the free Data Query Service (DQS).
27 Oct 2021 - Email Geeks
What the experts say
2 expert opinions
Spamhaus may block RBL queries due to excessive querying without proper caching, or due to underlying issues that lead to blacklisting. Solutions involve implementing caching and reducing query frequency, and understanding the blacklist's requirements and addressing issues like spam complaints or compromised accounts.
Key opinions
- Excessive Querying: Excessive RBL querying without caching or respecting TTL can cause temporary blocking.
- Underlying Issues: Blacklisting often stems from underlying problems such as spam complaints or compromised accounts.
Key considerations
- Implement Caching: Cache RBL results to reduce query frequency.
- Reduce Query Frequency: Limit the frequency of RBL queries.
- Understand Blacklist Requirements: Check the specific blacklist's requirements for delisting.
- Address Underlying Issues: Resolve the issues (e.g., spam complaints, compromised accounts) causing the listing.
Expert view
Expert from Spam Resource (referencing Halon) explains that excessive querying of RBLs, especially without proper caching or respect for TTL values, can lead to temporary blocking. They recommend implementing caching and reducing query frequency.
30 Jul 2021 - Spam Resource
Expert view
Expert from Word to the Wise suggests that understanding why you're blacklisted is crucial. They recommend checking the specific blacklist's requirements for delisting and addressing the underlying issues causing the listing (e.g., spam complaints, compromised accounts).
19 Jan 2022 - Word to the Wise
What the documentation says
5 technical articles
Spamhaus blocks RBL queries due to exceeding usage limits, using open resolvers, or association with malicious activities. OVHcloud users should migrate to the DQS. Spamhaus maintains lists like SBL and ZEN which identify IPs involved in spam or malware. The DQS offers a solution for high-volume lookups.
Key findings
- Usage Limits & Resolvers: Queries can be blocked for exceeding usage limits or using open resolvers.
- OVHcloud Requirement: OVHcloud users must migrate to the free Data Query Service (DQS).
- SBL Listing: The SBL lists IPs involved in direct spam or malware activities; review the reason for listing.
- ZEN Listing: ZEN combines SBL, XBL, and PBL; listing means presence on at least one.
- Data Query Service (DQS): DQS facilitates high-volume lookups without excessive query blocking.
Key considerations
- Check Return Codes: Check return codes to understand the reason for blocking.
- Take Corrective Action: If listed, take corrective action based on the listing reason.
- Consider DQS: Use DQS for high-volume DNSBL lookups.
Technical article
Documentation from Spamhaus specifies that if you query Spamhaus projects' DNSBLs via OVHcloud's DNS, you need to migrate to the free Data Query Service (DQS) due to changes in how OVHCloud's IP space is handled.
4 Feb 2022 - Spamhaus.org
Technical article
Documentation from Spamhaus explains that the SBL lists IP addresses involved in direct spam operations, malware distribution, or other malicious activities. If listed, you should review Spamhaus's reason for listing and take corrective action.
15 Mar 2022 - Spamhaus.org
Besides Spamhaus, what blocklists are important for email marketers to monitor?
How can I get delisted from Spamhaus?
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How effective are RBLs and blocklists for preventing spam in 2022?
How should an ESP handle Spamhaus blocking complete IP ranges with legitimate email?
Should I use a backup ESP when my primary ESP is blocked by Spamhaus?
