Suped

Spamhaus ZEN Blocklist

The Spamhaus ZEN Blocklist is a powerful and comprehensive blacklist that combines four of Spamhaus's main IP-based blocklists into a single, efficient query to enhance protection against spam and malicious email traffic.

Spamhaus ZEN Blocklist
Blocklist checker
Check your domain or IP against 92 blocklists.
0spam.org logo0Spam
Blocklist icon
8086 Consultancy
abuse.ro logoabuse.ro
Blocklist icon
Abusix
wiki.alphanet.ch logoALPHANETanonmails.de logoAnonmails
Blocklist icon
Barracuda Networks
www.blockedservers.com logoBLOCKEDSERVERSdnsbl.calivent.com.pe logoCalivent Networkswww.spamcop.net logoCisco
Blocklist icon
dan.me.uk
Blocklist icon
DrMx
Blocklist icon
DroneBL
rbl.efnetrbl.org logoEFnet
Blocklist icon
Fabel
Blocklist icon
GBUdb
Blocklist icon
ImproWare
Blocklist icon
JIPPG Technologies
Blocklist icon
Junk Email Filter
www.justspam.org logoJustSpamwww.kempt.net logoKempt.net
Blocklist icon
Mail Baby
Blocklist icon
Mailspike
www.nordspam.com logoNordSpamwww.nosolicitado.org logoNoSolicitado
Blocklist icon
nsZones
Blocklist icon
RedHawk
rv-soft.info logoRV-SOFT Technology
Blocklist icon
Schulte
www.scientificspam.net logoScientific Spam
Blocklist icon
Spam Eating Monkey
www.spamhaus.org logoSpamhauspsbl.org logoSpamikazewww.spamrats.com logoSpamRATSspfbl.net logoSPFBLsuomispam.net logoSuomispam
Blocklist icon
SURBL
www.usenix.org.uk logoSystem 5 Hostingwww.team-cymru.com logoTeam Cymru
Blocklist icon
UCEPROTECT
uribl.com logoURIBLwww.blocklist.de logowww.blocklist.de Fail2Ban-Reporting Servicezapbl.net logoZapBL
Blocklist icon
Brukalai.lt
0spam.org logo0Spam
Blocklist icon
8086 Consultancy
abuse.ro logoabuse.ro
Blocklist icon
Abusix
wiki.alphanet.ch logoALPHANETanonmails.de logoAnonmails
Blocklist icon
Barracuda Networks
www.blockedservers.com logoBLOCKEDSERVERSdnsbl.calivent.com.pe logoCalivent Networkswww.spamcop.net logoCisco
Blocklist icon
dan.me.uk
Blocklist icon
DrMx
Blocklist icon
DroneBL
rbl.efnetrbl.org logoEFnet
Blocklist icon
Fabel
Blocklist icon
GBUdb
Blocklist icon
ImproWare
Blocklist icon
JIPPG Technologies
Blocklist icon
Junk Email Filter
www.justspam.org logoJustSpamwww.kempt.net logoKempt.net
Blocklist icon
Mail Baby
Blocklist icon
Mailspike
www.nordspam.com logoNordSpamwww.nosolicitado.org logoNoSolicitado
Blocklist icon
nsZones
Blocklist icon
RedHawk
rv-soft.info logoRV-SOFT Technology
Blocklist icon
Schulte
www.scientificspam.net logoScientific Spam
Blocklist icon
Spam Eating Monkey
www.spamhaus.org logoSpamhauspsbl.org logoSpamikazewww.spamrats.com logoSpamRATSspfbl.net logoSPFBLsuomispam.net logoSuomispam
Blocklist icon
SURBL
www.usenix.org.uk logoSystem 5 Hostingwww.team-cymru.com logoTeam Cymru
Blocklist icon
UCEPROTECT
uribl.com logoURIBLwww.blocklist.de logowww.blocklist.de Fail2Ban-Reporting Servicezapbl.net logoZapBL
Blocklist icon
Brukalai.lt
0spam.org logo0Spam
Blocklist icon
8086 Consultancy
abuse.ro logoabuse.ro
Blocklist icon
Abusix
wiki.alphanet.ch logoALPHANETanonmails.de logoAnonmails
Blocklist icon
Barracuda Networks
www.blockedservers.com logoBLOCKEDSERVERSdnsbl.calivent.com.pe logoCalivent Networkswww.spamcop.net logoCisco
Blocklist icon
dan.me.uk
Blocklist icon
DrMx
Blocklist icon
DroneBL
rbl.efnetrbl.org logoEFnet
Blocklist icon
Fabel
Blocklist icon
GBUdb
Blocklist icon
ImproWare
Blocklist icon
JIPPG Technologies
Blocklist icon
Junk Email Filter
www.justspam.org logoJustSpamwww.kempt.net logoKempt.net
Blocklist icon
Mail Baby
Blocklist icon
Mailspike
www.nordspam.com logoNordSpamwww.nosolicitado.org logoNoSolicitado
Blocklist icon
nsZones
Blocklist icon
RedHawk
rv-soft.info logoRV-SOFT Technology
Blocklist icon
Schulte
www.scientificspam.net logoScientific Spam
Blocklist icon
Spam Eating Monkey
www.spamhaus.org logoSpamhauspsbl.org logoSpamikazewww.spamrats.com logoSpamRATSspfbl.net logoSPFBLsuomispam.net logoSuomispam
Blocklist icon
SURBL
www.usenix.org.uk logoSystem 5 Hostingwww.team-cymru.com logoTeam Cymru
Blocklist icon
UCEPROTECT
uribl.com logoURIBLwww.blocklist.de logowww.blocklist.de Fail2Ban-Reporting Servicezapbl.net logoZapBL
Blocklist icon
Brukalai.lt
0spam.org logo0Spam
Blocklist icon
8086 Consultancy
abuse.ro logoabuse.ro
Blocklist icon
Abusix
wiki.alphanet.ch logoALPHANETanonmails.de logoAnonmails
Blocklist icon
Barracuda Networks
www.blockedservers.com logoBLOCKEDSERVERSdnsbl.calivent.com.pe logoCalivent Networkswww.spamcop.net logoCisco
Blocklist icon
dan.me.uk
Blocklist icon
DrMx
Blocklist icon
DroneBL
rbl.efnetrbl.org logoEFnet
Blocklist icon
Fabel
Blocklist icon
GBUdb
Blocklist icon
ImproWare
Blocklist icon
JIPPG Technologies
Blocklist icon
Junk Email Filter
www.justspam.org logoJustSpamwww.kempt.net logoKempt.net
Blocklist icon
Mail Baby
Blocklist icon
Mailspike
www.nordspam.com logoNordSpamwww.nosolicitado.org logoNoSolicitado
Blocklist icon
nsZones
Blocklist icon
RedHawk
rv-soft.info logoRV-SOFT Technology
Blocklist icon
Schulte
www.scientificspam.net logoScientific Spam
Blocklist icon
Spam Eating Monkey
www.spamhaus.org logoSpamhauspsbl.org logoSpamikazewww.spamrats.com logoSpamRATSspfbl.net logoSPFBLsuomispam.net logoSuomispam
Blocklist icon
SURBL
www.usenix.org.uk logoSystem 5 Hostingwww.team-cymru.com logoTeam Cymru
Blocklist icon
UCEPROTECT
uribl.com logoURIBLwww.blocklist.de logowww.blocklist.de Fail2Ban-Reporting Servicezapbl.net logoZapBL
Blocklist icon
Brukalai.lt
0spam.org logo0Spam
Blocklist icon
8086 Consultancy
abuse.ro logoabuse.ro
Blocklist icon
Abusix
wiki.alphanet.ch logoALPHANETanonmails.de logoAnonmails
Blocklist icon
Barracuda Networks
www.blockedservers.com logoBLOCKEDSERVERSdnsbl.calivent.com.pe logoCalivent Networkswww.spamcop.net logoCisco
Blocklist icon
dan.me.uk
Blocklist icon
DrMx
Blocklist icon
DroneBL
rbl.efnetrbl.org logoEFnet
Blocklist icon
Fabel
Blocklist icon
GBUdb
Blocklist icon
ImproWare
Blocklist icon
JIPPG Technologies
Blocklist icon
Junk Email Filter
www.justspam.org logoJustSpamwww.kempt.net logoKempt.net
Blocklist icon
Mail Baby
Blocklist icon
Mailspike
www.nordspam.com logoNordSpamwww.nosolicitado.org logoNoSolicitado
Blocklist icon
nsZones
Blocklist icon
RedHawk
rv-soft.info logoRV-SOFT Technology
Blocklist icon
Schulte
www.scientificspam.net logoScientific Spam
Blocklist icon
Spam Eating Monkey
www.spamhaus.org logoSpamhauspsbl.org logoSpamikazewww.spamrats.com logoSpamRATSspfbl.net logoSPFBLsuomispam.net logoSuomispam
Blocklist icon
SURBL
www.usenix.org.uk logoSystem 5 Hostingwww.team-cymru.com logoTeam Cymru
Blocklist icon
UCEPROTECT
uribl.com logoURIBLwww.blocklist.de logowww.blocklist.de Fail2Ban-Reporting Servicezapbl.net logoZapBL
Blocklist icon
Brukalai.lt

What is Spamhaus ZEN Blocklist?

The Spamhaus ZEN Blocklist is a powerful and comprehensive IP-based DNSBL (DNS Blocklist) that combines all of Spamhaus's individual IP blacklists into a single, efficient list. Its main purpose is to simplify and speed up the process of querying for malicious IP addresses. ZEN includes several component blocklists, each with its own specific policy for listing IPs.

Email administrators at internet service providers, corporations, and other organizations use this blocklist to filter incoming email traffic. By using ZEN, they can significantly reduce the volume of spam, phishing attempts, and other malicious emails reaching their users. This helps lower security risks, reduces infrastructure costs, and saves time for security teams. A fun fact is that the blacklist was named after Spamhaus founder Steve Linford's German Shepherd, Zen, who has now passed on but continues to help guard networks.

What's included in ZEN?

ZEN combines the data from the following Spamhaus IP blacklists, each targeting a specific type of threat:

  • Spamhaus Blocklist (SBL): Lists IPs that are verified sources of spam.
  • Combined Spam Sources blocklist (CSS): Lists IPs exhibiting spam-like behavior, including those sending unsolicited bulk email.
  • Exploits Blocklist (XBL): Contains IPs of hijacked PCs, servers, and other devices infected with malware, viruses, or trojans.
  • Policy Blocklist (PBL): Includes IP addresses that should not be sending email directly to the internet, such as dynamic IP ranges for home internet users.

Technical information

When a mail server queries the Spamhaus ZEN Blocklist about an IP address, it typically receives multiple answers in a single DNS response if the IP is listed on more than one component blacklist. Each answer has a distinct return code corresponding to the specific blocklist (SBL, CSS, XBL, or PBL) the IP is on. This method provides detailed information efficiently, using fewer resources than querying each list separately. This data can be used directly in an SMTP server configuration or with open source tools like SpamAssassin and Rspamd for deeper content analysis.

Who runs Spamhaus ZEN Blocklist?

The Spamhaus ZEN Blocklist is operated by Spamhaus Project, a non-profit organization and a trusted authority on IP and domain reputation. Founded by Steve Linford in 1998, Spamhaus began by tracking IP addresses sending spam and listing them on a DNSBL to help email administrators filter malicious mail. Today, Spamhaus has expanded its research to include IPs, domains, and ASNs associated with phishing, malware, and ransomware.

The organization's mission is to strengthen trust and safety across the internet. They provide intelligence to help filter email, protect networks, and offer reputation data to help owners monitor the health of their digital assets. Spamhaus works with the broader internet community, including law enforcement, to make the internet a safer place. While their core blocklist data is offered for free for non-commercial use, they partner with Spamhaus Technology to provide real-time data feeds for commercial users.

How do I get removed and delisted from Spamhaus ZEN Blocklist?

If your IP address is listed on the Spamhaus ZEN Blocklist, it means it is also present on one of its component lists: SBL, CSS, XBL, or PBL. To begin the removal process, you must first identify the specific reason for the listing. You can do this by using the IP and Domain Reputation Checker on the Spamhaus website. This tool will provide details about the listing and the necessary steps for remediation.

Before you request delisting, it is crucial to resolve the underlying issue that caused your IP to be flagged. Follow these best practices to fix the problem and maintain a positive IP reputation:

  • Restrict outbound traffic. Configure your firewall to only allow outbound SMTP traffic (on destination port 25) from your designated mail server.
  • Check your infrastructure. Review the reputation of your internet service providers and network providers.
  • Use double opt-in. This practice helps ensure your mailing lists are clean, avoids spam traps, and confirms you are only sending emails to genuinely interested recipients.
  • Verify your configuration. Ensure your server's hostname and HELO command match. Your reverse DNS (PTR record) should also be correctly defined and point to the same hostname.

After you have addressed the root cause, you can follow the delisting procedure provided by the checker tool. Remember that some of these issues may require coordination with network administrators or deliverability specialists.

What's the impact of being listed on Spamhaus ZEN Blocklist?

The impact of being listed on the Spamhaus ZEN Blocklist is high. Because ZEN is a composite blacklist (or blocklist) used by a vast number of organizations worldwide, a listing can severely harm your email deliverability. Mail servers using this blocklist will likely reject or filter emails sent from your IP address, preventing your messages from reaching their intended recipients. Since a listing on ZEN means your IP is also on a more specific blacklist like the SBL or XBL, it signals a significant issue that mail providers take seriously.

Other Spamhaus blocklists

Blocklist guides

19 resources

Start improving your email deliverability today

Get started