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What to Do If Your Email Is Blacklisted

What to Do If Your Email Is Blacklisted

If your outgoing emails are being rejected or bouncing back with errors mentioning "blacklist," "blocklist," or "denied," your mail server's IP address may have been added to an email blacklist (also called a blocklist or DNSBL). This guide explains why blacklisting happens, how to check your status, and the steps to get delisted.

What Is an Email Blacklist?

Email blacklists are databases maintained by organizations like Spamhaus, Barracuda, SpamCop, and others. These databases contain IP addresses and domains that have been identified as sources of spam or malicious email.

When a receiving mail server gets a message from your server, it checks the sending IP against one or more blacklists. If the IP is listed, the email may be:

  • Rejected outright — bounced back with an error
  • Flagged as spam — delivered to the spam folder
  • Delayed — held in a temporary queue

Signs Your Email Is Blacklisted

  1. Bounce-back messages containing phrases like:

- "rejected by blacklist"

- "listed on DNSBL"

- "blocked by Spamhaus"

- "554 5.7.1 Service unavailable"

  1. Emails consistently going to spam at major providers
  2. Sudden drop in email deliverability — recipients stop receiving your emails
  3. Delayed delivery — emails take hours to arrive

How to Check If You Are Blacklisted

Step 1: Find Your Mail Server IP

Your mail server IP is the IP address of the server that sends your outgoing email. You can find this in:

  • Your {{COMPANY_NAME}} welcome email
  • Your hosting control panel under Server Information
  • By running: dig A mail.yourdomain.com +short

Step 2: Check Against Major Blacklists

Use these free tools to check your IP against multiple blacklists simultaneously:

  1. MXToolbox Blacklist Check: https://mxtoolbox.com/blacklists.aspx
  2. MultiRBL: http://multirbl.valli.org/
  3. Spamhaus Lookup: https://check.spamhaus.org/

Enter your mail server IP address and the tool will check it against dozens of blacklists.

Common Reasons for Blacklisting

ReasonDescription
Compromised accountA hacked email account is sending spam
Infected websiteMalware on your website is sending spam through your server
Open relayYour mail server accepts and forwards email from anyone
Bulk email without consentSending newsletters to people who did not opt in
Poor list hygieneSending to old, invalid, or purchased email lists
Shared hostingAnother user on the same server is sending spam (shared IP)
Missing authenticationNo SPF, DKIM, or DMARC records

Steps to Get Delisted

Step 1: Identify and Fix the Root Cause

Before requesting delisting, you must stop the behavior that caused the listing. If you request removal without fixing the problem, you will be relisted quickly.

  1. Check for compromised accounts — Change passwords for all email accounts. Look for accounts sending high volumes.
  2. Scan for malware — Run a security scan on your website (e.g., using Imunify360 or ClamAV)
  3. Review outgoing mail queue — In cPanel, check Email → Track Delivery for suspicious outbound messages
  4. Secure your forms — Add CAPTCHA to contact forms to prevent abuse
  5. Update software — Ensure CMS, plugins, and scripts are up to date

Step 2: Request Delisting

Each blacklist has its own delisting process. Here are the major ones:

Spamhaus (SBL/XBL/PBL):

  1. Go to https://check.spamhaus.org/
  2. Enter your IP and follow the removal instructions
  3. Spamhaus typically processes requests within 24 hours

Barracuda (BRBL):

  1. Go to http://www.barracudacentral.org/lookups
  2. Enter your IP and request removal
  3. Removal usually takes 12–24 hours

SpamCop:

  1. SpamCop listings expire automatically after 24–48 hours if no new spam is reported
  2. No manual delisting process — just stop the spam

SORBS:

  1. Go to http://www.sorbs.net/
  2. Look up your IP and follow the delisting procedure
  3. Some SORBS zones require a fee for expedited delisting

Microsoft/Outlook (SNDS):

  1. Go to https://sendersupport.olc.protection.outlook.com/snds/
  2. Register your IP and request mitigation

Gmail:

  1. Gmail does not maintain a public blacklist
  2. Fill out the Gmail Postmaster Tools form
  3. Ensure SPF, DKIM, and DMARC are configured

Step 3: Monitor After Delisting

  1. Set up regular monitoring at MXToolbox (they offer free daily checks)
  2. Watch your outgoing mail queue for suspicious activity
  3. Review mail logs weekly for the first month

Preventing Future Blacklisting

  1. Use strong passwords for all email accounts (12+ characters, mixed case, numbers, symbols)
  2. Enable two-factor authentication where possible
  3. Set up SPF, DKIM, and DMARC records for your domain
  4. Limit outgoing email rates — Configure per-account sending limits in cPanel
  5. Monitor your server — Set up alerts for unusual outgoing email volume
  6. Use dedicated IPs for bulk sending — Never send marketing email from your main business IP
  7. Keep mailing lists clean — Remove bounced addresses promptly
  8. Use double opt-in for newsletter subscriptions

When to Contact {{COMPANY_NAME}} Support

Contact us if:

  • You cannot identify the source of the spam
  • The blacklisting is due to a shared hosting IP (another customer's actions)
  • You need help securing a compromised account or website
  • Delisting requests are being denied

We can investigate server-level issues, change your server's outgoing IP if necessary, and assist with the delisting process.

Related Articles

Blacklisted and need urgent help? Contact our support team at {{SUPPORT_URL}} or email {{SUPPORT_EMAIL}}. We prioritize blacklist issues to minimize impact on your business.

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