Why do IPs get blacklisted?

Common causes include open relays, compromised hosts sending spam or phishing, bulletproof hosting behavior, snowshoe spam patterns, or previous tenant misbehavior on shared cloud IPs. Some lists target policy violations (e.g., dynamic/residential space that should not originate bulk mail).

How do I get delisted?

Fix the root cause first—patch malware, close relays, rotate compromised credentials, warm up new mail properly. Then follow each list’s web form or automated removal process; some delist automatically after TTL when spam stops, others require manual review. Expect multi-hour to multi-day propagation.

A DNS-based Blackhole List publishes listings as DNS queries (often under specific zones). Mail servers query these zones during SMTP; a positive hit can trigger rejection or scoring. Lists differ in policy, coverage, and false-positive tolerance—no single list defines global truth.

Will one blacklist break all my email?

Impact depends on which receiving networks query which lists. Major consumer providers blend many signals. A listing on a niche list might be harmless; a listing on a widely consulted list can tank inbox placement. Monitor aggregate reputation dashboards and SMTP bounce codes.

How does this relate to IP WHOIS?

WHOIS tells you who operates the netblock for abuse contact and ASN context; blacklists tell you whether mailbox providers currently distrust that IP. Use [IP WHOIS](/ip-whois) to open tickets with the right hoster while you remediate listings.

IP Blacklist

v1.1.0

Quickly determine if an IP or range appears on major email and security blacklists. See which blacklists flagged the IP.

Blacklist check results will appear here

See whether a public IP appears on common DNSBLs and reputation lists. Use it when diagnosing bounces, warming new mail infrastructure, or investigating a compromised host.

Read the full guide →

Frequently Asked Questions

Why do IPs get blacklisted?: Common causes include open relays, compromised hosts sending spam or phishing, bulletproof hosting behavior, snowshoe spam patterns, or previous tenant misbehavior on shared cloud IPs. Some lists target policy violations (e.g., dynamic/residential space that should not originate bulk mail).
How do I get delisted?: Fix the root cause first—patch malware, close relays, rotate compromised credentials, warm up new mail properly. Then follow each list’s web form or automated removal process; some delist automatically after TTL when spam stops, others require manual review. Expect multi-hour to multi-day propagation.
What is a DNSBL?: A DNS-based Blackhole List publishes listings as DNS queries (often under specific zones). Mail servers query these zones during SMTP; a positive hit can trigger rejection or scoring. Lists differ in policy, coverage, and false-positive tolerance—no single list defines global truth.
Will one blacklist break all my email?: Impact depends on which receiving networks query which lists. Major consumer providers blend many signals. A listing on a niche list might be harmless; a listing on a widely consulted list can tank inbox placement. Monitor aggregate reputation dashboards and SMTP bounce codes.
How does this relate to IP WHOIS?: WHOIS tells you who operates the netblock for abuse contact and ASN context; blacklists tell you whether mailbox providers currently distrust that IP. Use [IP WHOIS](/ip-whois) to open tickets with the right hoster while you remediate listings.