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Blacklist / DNSBL Monitoring

Know if your server IP is listed on spam block lists.

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Blacklist monitoring checks your server's IP address against major DNS-based block lists (DNSBL). Being listed destroys email deliverability and can cause inbound email to be rejected.

⚙️How it works

Uptrue resolves your domain to its IP address and performs reverse DNS lookups against four major block list zones: Spamhaus ZEN, SpamCop, SORBS, and Barracuda. If any returns a positive result, an alert fires.

✓What Uptrue checks

  • Spamhaus ZEN (zen.spamhaus.org)
  • SpamCop (bl.spamcop.net)
  • SORBS (dnsbl.sorbs.net)
  • Barracuda (b.barracudacentral.org)

⚠Alert conditions

  • Domain IP listed on one or more DNSBL zones
Why this matters

Getting listed on Spamhaus can cause your emails to be rejected by millions of recipients overnight. Shared hosting and cloud IP ranges are especially vulnerable to neighbour listings.

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?Frequently asked questions

What do I do if I'm listed?
Each block list has a delisting process. Spamhaus and Barracuda have web forms. Fix the underlying spam/abuse issue first.
Which block lists do you check?
Spamhaus ZEN, SpamCop, SORBS, and Barracuda Central — the four most widely used.
Related Monitor Types
📧MX Health Monitoring✉️SPF / DMARC Monitoring
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Ready to set up Blacklist / DNSBL Monitoring?

Join teams who monitor their infrastructure with Uptrue. Free plan, no credit card required. Want to spot-check first? Run our free domain blacklist checker.

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