Blacklist & Reputation Guides

Checking If Your IP or Domain Is on a Blacklist

Learn how to check if your sending IP or domain is blacklisted, how to interpret results, and what to fix before requesting delisting.

By CheckDomainHealth Editorial Team Reviewed by Dionis Ceban Updated Jun 28, 2026 8 min read Beginner

Introduction

Blacklist checking helps you find whether a sending IP address, mail server hostname, domain or URL is listed on reputation databases used by some email filters. These listings can affect email delivery, especially when sending from shared hosting, VPS servers, transactional mail systems or bulk email platforms.

A blacklist result does not always mean all email is blocked. Some receivers use blacklist data as a hard rejection, while others use it as one signal together with SPF, DKIM, DMARC, reverse DNS, content quality, complaint history and sending behavior.

Quick answer

Quick answer

To check blacklist status, test the real sending IP address, mail hostname, domain, reverse DNS and links used in your emails. If you find a listing, identify the exact blacklist and reason before requesting delisting. Fix spam, malware, authentication or reputation issues first.

What to check

Blacklist checks can involve more than one identifier.

  • Sending IP address
  • Mail server hostname
  • Reverse DNS hostname
  • Domain used in From address
  • Return-path or bounce domain
  • Domain links inside the email
  • MX hostname
  • Shared hosting or VPS IP reputation

For email delivery, the sending IP is often the most important first check, but domain reputation also matters.

IP vs domain listing

IP blacklist

  • Lists the server or network address that sends mail.
  • Common causes: spam from server, compromised account, open relay, poor shared IP reputation, malware or suspicious sending volume.

Domain blacklist

  • Lists a domain associated with spam, phishing, malware, suspicious links or poor reputation.
  • Common causes: phishing content, spam links, compromised website, bad email campaigns or domain abuse.

An IP can be clean while a domain is listed, and a domain can be clean while the sending IP is listed.

Find sending IP

Before checking blacklists, confirm which IP actually sends the email.

  • Bounce message
  • Email headers
  • Mail server logs
  • SMTP provider dashboard
  • Hosting control panel
  • Transactional email provider logs

Do not assume your website IP is the same as your email sending IP. Many domains use separate mail providers such as Google Workspace, Microsoft 365, Mailgun, SendGrid, Amazon SES or hosting SMTP.

Interpret results

When a blacklist checker shows a listing, collect the details before taking action.

  • Which IP or domain is listed
  • Which blacklist provider lists it
  • Whether the listing is active
  • Whether a reason is provided
  • Whether recent bounce messages mention that list
  • Whether the IP is shared or dedicated
  • Whether your server recently sent unusual mail
  • Whether a website or mailbox was compromised

A listing on a small list may have little visible impact. A listing on a widely used list can affect delivery more seriously.

Why this matters

Why this matters

Blacklist checks matter because listings can reduce email deliverability and signal reputation problems. A listed IP may cause mail to bounce, land in spam, be deferred or receive stricter filtering. A listed domain can also hurt trust if it appears in message links, From addresses or return paths.

Recovery depends on fixing the root cause, not only requesting removal.

How to check

Use Blacklist Checker to test the IP address or domain involved in sending email.

  1. Sending IP — start with the IP shown in bounce messages or mail headers.
  2. Mail hostname — check the SMTP hostname used by the server.
  3. Reverse DNS — confirm PTR/rDNS matches the mail server identity.
  4. Domain reputation — check the domain used in From, return-path and links.
  5. Authentication — review SPF, DKIM and DMARC because weak authentication can worsen reputation.
  6. Bounce text — read the exact rejection message to identify the blocking list or provider.

Check blacklist status

Use Blacklist Checker to test the IP address or domain involved in sending email.

Run Blacklist Check →

Common problems

Sending IP listed

High

The IP used to send mail appears on one or more blacklist databases.

Next step: Identify the listing reason, stop abuse and follow the blacklist provider’s process.

Domain listed

High

The domain may be associated with spam, phishing, malware or suspicious links.

Next step: Check website security, email content, campaigns and domain reputation.

Shared IP reputation problem

Medium

Another user on the same hosting or mail IP may have caused poor reputation.

Next step: Contact the provider or move important mail to a cleaner dedicated sending service.

Wrong IP checked

Medium

The website IP was checked, but email is sent from another SMTP provider.

Next step: Find the real sending IP in email headers or bounce logs.

Missing or bad reverse DNS

Medium

PTR/rDNS does not match the mail server identity.

Next step: Set correct reverse DNS for the sending IP.

Weak SPF, DKIM or DMARC

Medium

Authentication problems make mail look less trustworthy.

Next step: Fix SPF, DKIM and DMARC before heavy sending.

Compromised account or script

High

A hacked mailbox, website script or CMS plugin may be sending spam.

Next step: Stop sending, clean malware, reset passwords and inspect logs.

Delisting requested without cleanup

High

If abuse continues, the IP or domain may be listed again.

Next step: Fix the source first, then request removal.

What to do if listed

  1. Step 1: Confirm the exact listed item

    Record the IP address, domain, hostname and blacklist name.

  2. Step 2: Read the reason

    Check the blacklist result, bounce message or provider page for the listing reason.

  3. Step 3: Stop suspicious sending

    Pause bulk campaigns, disable compromised accounts and block abusive scripts.

  4. Step 4: Check server and website security

    Scan websites, plugins, mail accounts, cron jobs and outbound logs.

  5. Step 5: Fix mail identity

    Review rDNS, HELO/EHLO, SPF, DKIM, DMARC and MX configuration.

  6. Step 6: Clean recipient lists

    Remove invalid, old, purchased or unconfirmed addresses.

  7. Step 7: Request delisting

    Use the official delisting process only after fixing the cause.

  8. Step 8: Monitor reputation

    Watch bounce logs, blacklist status and sending volume after removal.

What not to do

Avoid these mistakes after finding a listing.

  • Requesting delisting before cleanup
  • Checking only the domain and ignoring the sending IP
  • Ignoring bounce messages
  • Continuing bulk sending during investigation
  • Changing IPs without fixing the cause
  • Blaming the blacklist before checking compromise
  • Using shared hosting for high-volume mail
  • Assuming one clean checker means everything is fine

A new IP can also become listed if the same sending behavior continues.

Examples

Example bounce 
550 5.7.1 Message rejected because 192.0.2.10 is listed on example.dnsbl
What to check 
Sending IP: 192.0.2.10
Mail hostname: mail.example.com
Reverse DNS: mail.example.com
SPF: pass/fail
DKIM: pass/fail
DMARC: pass/fail
Blacklist: example.dnsbl
Recent outbound spike: yes/no
Compromise found: yes/no
DNSBL-style lookup 
192.0.2.10
→ 10.2.0.192.dnsbl.example

Examples are illustrative. Use real blacklist lookup tools, mail logs and official blacklist pages for live cases.

Frequently asked questions

Does a blacklist listing always block email?

No. Some receivers block listed mail, while others use blacklist data as one reputation signal.

Should I check my IP or domain?

Check both, but start with the real sending IP from headers, logs or bounce messages.

Why is my domain clean but email still bounces?

The sending IP, mail hostname or shared mail server may be listed instead.

Why is my IP listed if I did not send spam?

The IP may be shared, previously abused, compromised or part of a poor-reputation network.

Can I delist immediately?

Only after fixing the cause. Delisting too early often leads to re-listing.

How long does delisting take?

It depends on the blacklist provider and whether the abuse has stopped.

How do I prevent future listings?

Secure accounts, monitor outbound mail, use SPF/DKIM/DMARC, maintain rDNS and avoid risky bulk sending.

Use these free tools to verify your configuration after applying changes.

Blacklist Checker Reverse DNS Checker MX Lookup SPF Checker DKIM Checker DMARC Checker Domain Health Checker
What Is a DNSBL and How Does It Work 8 min read Major DNSBL Providers: Spamhaus, SpamCop and Barracuda 8 min read How to Get Your IP Delisted from a Blacklist 8 min read Avoiding Re-Listing: Maintaining a Clean Sending Reputation 8 min read Understanding Domain Reputation and Sender Score 9 min read
Browse all Blacklist & Reputation guides →

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