Reputation

How to Check If Your IP Is Blacklisted (and Get It Removed)

If your transactional emails are bouncing or your server is suddenly being refused, your IP may be on a blocklist. Find your IP first, then check the major lists.

Looking up IP details…

How blocklists work

A DNSBL is a specially formatted DNS zone. Mail servers issue a regular DNS query for your IP's reversed octets against the blocklist's zone (e.g. 4.3.2.1.zen.spamhaus.org). A response means listed; NXDOMAIN means clean. Because it's just DNS, lookups are fast and free.

Which lists to check

Spamhaus ZEN — meta-list covering SBL, XBL, and PBL. Listed here = serious deliverability issues.
Barracuda Reputation Block List — widely consulted by enterprise mail servers.
SORBS DUHL / SPAM — separate lists for dynamic IPs and known spam sources.
SpamCop — fast-acting list based on user reports.
UCEPROTECT (L1/L2/L3) — aggressive lists; L2/L3 can block whole ASNs.

When you find a listing

Find the root cause: compromised account, vulnerable form, unauthenticated SMTP, or shared-host neighbor abuse.
Fix it. Rotate credentials, patch the form, enable SPF/DKIM/DMARC, harden the relay.
Wait until you have no fresh complaints for at least a few hours.
Submit the delisting request from the blacklist's site. Provide remediation details.
Monitor — many lists relist automatically if abuse continues.

Don't get caught off guard again

Blacklisting is silent — there's no notification. Schedule a recurring reputation check from your dashboard so you find out the same hour your IP gets listed, not when sales emails start bouncing days later.

Recommended next steps

Diagnostic workflow

1
Find your public IP
Confirm the address you actually send from.
IP checker
2
Verify DNS records
SPF, DKIM, and DMARC misconfigurations cause listings.
DNS lookup
3
Confirm your mail server responds
Rule out connection issues before chasing blocklists.
Server status
4
Monitor reputation
Recurring blacklist checks with alerts.
Open dashboard

Frequently asked questions

What's an IP blacklist?

A reputation database — usually called a DNSBL or RBL — that catalogs IPs reported for spam, malware, brute-force attacks, or other abuse. Mail servers query these lists before accepting mail.

Which blacklists matter most?

Spamhaus (SBL, XBL, PBL), Barracuda, SORBS, and SpamCop have the largest impact on email deliverability. Most mail providers consult several at once.

How does an IP end up listed?

Compromised mail server sending spam, a customer phishing campaign, dynamic IP previously used by a spammer, or open-relay / open-resolver misconfigurations.

Will my email go to spam if I'm listed?

Usually it gets rejected outright with a 5xx error referring to the blacklist. Sometimes it lands in spam. Either way, deliverability drops sharply.

How do I get delisted?

Fix the root cause first (otherwise you'll be relisted within hours). Then submit a delisting request on the blacklist's site. Most respond within 24–48 hours.