ALPHANET Blackholes RBL DNS Blacklist
ALPHANET Blackholes is a volunteer-run blacklist (blocklist) for malicious IPv4 addresses. Removals happen automatically after one week of inactivity.
Updated on 17 Jun 2026: We updated this guide with clearer DNSBL lookup behavior, delisting checks, and expected delivery impact.
Summarize with
Check if you are listed on ALPHANET Blackholes RBL DNS Blacklist
And 143 other blocklists.
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 is ALPHANET Blackholes RBL DNS blacklist?
The ALPHANET Blackholes RBL DNS Blacklist is a public blacklist (blocklist) that lists IPv4 addresses that have exhibited malicious behavior. It is an IP-based DNSBL, so it focuses on sending hosts and network sources rather than domains, URLs, or email identities. ALPHANET uses it to block access to its own services, and other system administrators can incorporate the list into their security controls.
This DNS blacklist is populated with data collected from several sources. ALPHANET operates spam traps and honeypots across different Autonomous Systems (ASes). Logs from real services also help identify offending IP addresses. The criteria for adding an IP to this blacklist are straightforward:
- The IP address exhibits bad behavior, such as sending spam, scanning services, or attempting to breach systems, as detected by ALPHANET's infrastructure.
- The IP has been reported for malicious activity by a trusted third party.
Technically, the blacklist is available in two forms: as a Real-time Blackhole List (RBL) for DNS queries and as a downloadable file containing the complete list of IPs and CIDR subnets. ALPHANET notes that the DNS list is not complete for technical reasons and advises against using it in high-traffic environments.
How ALPHANET Blackholes DNSBL lookups work
A DNSBL lookup checks a connecting IPv4 address through DNS before a receiving system accepts, rejects, or scores a connection. The mail server reverses the IPv4 octets, appends the ALPHANET DNSBL zone configured locally, then queries DNS for a result.
- A positive A record response means the queried IP is listed on the blacklist (blocklist).
- An NXDOMAIN or no-match response means the queried IP is not listed in that DNSBL response.
- A TXT response, when available, gives extra listing context that helps with investigation and delisting.
Because ALPHANET says the DNS feed is incomplete and not intended for high-volume querying, administrators who need fuller coverage should use the downloadable IP and CIDR data where that fits their filtering stack.
Who runs ALPHANET Blackholes RBL DNS blacklist?
The ALPHANET Blackholes RBL DNS Blacklist is operated by ALPHANET, a non-profit organization that has provided free community services since 1987. The organization's stated goal is to promote free and open systems in telecommunications while providing reliable and sustainable services.
ALPHANET's charter emphasizes technical independence, open-source solutions, and long-term social responsibility. Its history began with a telematic server in 1987 and continued through later infrastructure and community services.
How do I get removed from ALPHANET Blackholes RBL DNS blacklist?
ALPHANET has an automated delisting process. IPs are typically removed from the blacklist automatically after one week if the malicious activity has stopped. Removal takes longer when the same IP keeps triggering new detections or when ALPHANET still sees active abuse.
Before requesting manual removal, fix the issue that caused the listing. Check mail queues, authentication failures, compromised web forms, open relays, proxy abuse, malware, and unexpected outbound SMTP traffic. If the address is a shared or hosted IP, involve the provider that controls the server or network.
Once the system has been secured, request unblocking by contacting ALPHANET's support team. They process removals when the IP is no longer actively attacking. Send the delisting request by email to blackholes@alphanet.ch.
What's the impact of being listed on ALPHANET Blackholes RBL DNS blacklist?
The impact of being on the ALPHANET Blackholes RBL DNS Blacklist is usually limited to networks that explicitly query it. Major mailbox providers rely heavily on their own internal filters and a small number of high-impact DNSBLs, so this listing alone usually does not explain broad inbox placement problems.
Some system administrators and organizations use this blocklist to filter incoming connections and email traffic. If your IP is listed, expect isolated SMTP rejections, connection blocks, or access failures at systems that use this specific blacklist. Treat it as a sign to investigate abuse quickly, even when the overall deliverability impact is low.
