Blocklist detection

A blocklist listing means mailbox providers that check that list will reject or filter your mail — often without any bounce message that makes it obvious what happened. InboxEagle monitors your sending IPs and domains against major DNS-based blocklists (DNSBLs) in real time and alerts you the moment a listing is detected.

Blocklists monitored

InboxEagle monitors the following blocklists, organized by impact:

Blocklist	Type	Impact
Spamhaus SBL	IP	Very high — used by most major ISPs and enterprises
Spamhaus XBL	IP	Very high — compromised/infected IP listing
Spamhaus PBL	IP	High — residential/dynamic IP ranges (not mail servers)
Spamhaus DBL	Domain	High — domain in links or From address
Barracuda BRBL	IP	High — widely used by corporate mail filters
SpamCop	IP	Medium — complaint-based, expires naturally
SORBS	IP/Domain	Medium — multiple SORBS zones; impact varies

Note

A Spamhaus SBL or Barracuda listing causes delivery failures at most major ISPs and enterprise mail servers. Treat these as highest priority. SpamCop and lower-tier SORBS zones have narrower impact but are still worth resolving quickly.

Domain vs IP listings

IP listings (SBL, XBL, PBL, Barracuda, SpamCop, SORBS) affect delivery at the network level. When your sending IP is listed, providers that check that DNSBL will reject your messages during the SMTP connection — before they even see the content or From address.

Domain listings (DBL) affect the domain found in your email’s From: address, subject line links, or unsubscribe URLs. DBL listings can cause filtering even when your sending IP is clean.

InboxEagle monitors both. The alert specifies which IP or domain was listed and on which blocklist.

Alerts

When InboxEagle detects a new listing, an alert fires within minutes. The alert includes:

• The listed IP address or domain
• Which blocklist it appeared on
• The time the listing was first detected
• A direct link to the blocklist’s lookup page for that IP/domain

To configure alert delivery (email, in-app, or both), go to Account → Notification settings.

Respond to a listing

Caution

Pause sending from the listed IP immediately. Continuing to send from a listed IP while investigating generates more complaints and complaints, making delisting harder and recovery slower. For shared IPs, contact your ESP — they manage shared pool reputation and may need to move you to a different IP.

Before requesting removal, diagnose the root cause:

1. Review bounce and complaint data from the past 2–4 weeks for the sending IP or domain
2. Identify the campaign or list segment most likely to have triggered the listing
3. Check your authentication: if the listing reason mentions spam or phishing, confirm your SPF, DKIM, and DMARC are all passing (DMARC monitoring)
4. If your account was compromised, rotate credentials and revoke unauthorized access before sending again

Removal steps by blocklist

1. Spamhaus (SBL, XBL, DBL)

   Look up the listing reason at spamhaus.org/lookup. After fixing the root cause, submit a removal request through the Spamhaus removal portal linked on the lookup page. SBL removals are manually reviewed; XBL removals are automated once the issue is resolved.

2. Barracuda BRBL

   Submit a removal request at barracudacentral.org/rbl/removal-request. Barracuda typically processes removal requests within 12 hours after the root cause is resolved.

3. SpamCop

   SpamCop listings expire automatically, typically within 24 hours after complaints stop arriving. No manual removal request is needed. Focus on reducing the complaint rate from the sending IP to prevent re-listing.

4. SORBS

   SORBS has multiple zones with different removal processes. Look up the specific zone at sorbs.net and follow the removal instructions for that zone. SORBS removal often requires a formal request with an abuse investigation summary.

5. Spamhaus PBL

   PBL listings are for IP ranges that should not be sending outbound email (residential, dynamic, and non-MTA ranges). If your IP is incorrectly listed, submit a removal request at the Spamhaus PBL removal portal. If your IP is correctly listed (e.g., it is a shared cloud IP that is not a dedicated mail server), contact your ESP — they should manage this.

Note

InboxEagle continues monitoring your IPs and domains after a delisting. If the root cause was not fully resolved, re-listing can occur within days. The listing history view shows all historical listing events so you can track recurrence.

Listing history

The blocklist detection dashboard shows:

• Current listing status for all monitored IPs and domains
• Historical listing events (which blocklist, listed/delisted dates, duration)
• Trend view: frequency of listings over the past 90 days

Repeated listings at the same blocklist signal a systemic problem — complaint rate, spam trap hits, or an ongoing sending practice that needs to be changed.

Next steps

• IP reputation monitoring — Full IP reputation detail view including blacklist status
• Improve inbox placement — List hygiene and complaint rate reduction
• DMARC monitoring — Detect unauthorized senders who may be triggering listings using your domain
• Glossary: Blocklist

View blocklist status →