SiteVerdict — Email Blacklist & Deliverability Checker

Find out whether your mail servers are on a blocklist, and why, before your emails start landing in spam.

Enter domains, IP addresses or email addresses. For each one the Actor:

• finds your mail-server (MX) IPs and the single-IP senders in your SPF record;
• checks them against DNS blocklists whose terms allow it;
• adds Spamhaus, Abusix and SpamRATS when you supply your own query keys;
• reports every listing with its reason and delisting link, plus a plain-English SPF / DKIM / DMARC summary.

Schedule it and you get an alert as soon as you are listed, and again when you are delisted.

Who it is for

• Businesses and ecommerce stores that need their order and marketing emails to arrive.
• Agencies and MSPs monitoring many client domains or mail servers.
• ESP and IT teams that want an automated daily blocklist check with history.

Accuracy first: no false "clean"

Most blocklists refuse lookups that come through big public DNS resolvers. Many checkers then silently report "not listed". This Actor first queries each list's RFC 5782 test entry (127.0.0.2 / test).

• If the list does not answer correctly from the resolver in use, its result is reported as unknown, never as clean.
• Refusal codes such as 127.255.255.254 are decoded and never mistaken for listings.

What you get per target

Field	Content
verdict	listed / clean / unknown
listings	List name, listed IP and its role (MX, SPF sender, input), return-code meaning, the list's TXT reason, delisting URL
ipsChecked	Each IP found, and where it came from
listsChecked / listsUnknown	Lists that answered reliably, and lists that did not (with the reason)
auth	MX hosts; SPF record, DNS-lookup count, all qualifier and errors; DMARC policy, pct and rua; DKIM keys found on 30+ common selectors with key size; plain-English notes
newlyListed / delisted	Changes since the last run (monitoring)

Exports:

• LISTINGS_CSV: one line per listing.
• SUMMARY: lists used with their terms, zone health, and excluded lists with the reason for each.

Run with Mode = Sample to see a listed domain, a listed IP and a clean domain, free. The sample uses documentation-only IP ranges.

Blocklists

List	Default	Why we may use it
PSBL	on	"Anybody is free to use PSBL."
DroneBL	on	Free for commercial and non-commercial use
UCEPROTECT Level 1	on	Permissive licence; DNS lookups suited to small and medium volumes
Spamhaus ZEN + DBL	on with your DQS key	Spamhaus' free public mirrors are non-commercial only and refuse cloud resolvers, so we never use them. Your own Data Query Service key works.
Abusix Mail Intelligence (IP + domain)	on with your key	Abusix offers a free tier with a query key
SpamRATS	on with your key	Free with a registered API key (not for commercial email-protection providers)
UCEPROTECT L2 / L3, Backscatterer	opt-in	Aggressive lists that block whole provider ranges; informational
SpamCop, Mailspike	opt-in	Widely used, but we found no published terms for third-party lookups
Barracuda, SURBL/URIBL, Spamhaus public mirrors	excluded	Registration or a commercial feed is required
SORBS, NiX Spam	excluded	Shut down

Monitoring and alerts

Set Output = Only changes and schedule a daily run. You get a row, plus a Slack or webhook alert, only when a target is newly listed or delisted. History is kept in the named state store.

Optional: AI remediation plan (your own key)

For listed or misconfigured targets, your Anthropic or OpenAI key turns the findings into a step-by-step plan:

• a diagnosis;
• DNS records to fix;
• per-list delisting instructions;
• prevention steps.

The key is stored encrypted and never logged.

Example input and output

Check one domain's mail servers against blocklists, plus SPF, DMARC and DKIM:

Input

{
  "targets": [
    "python.org"
  ]
}

Output (one dataset item, trimmed; real result from a test run on 14 Oct 2026)

{
  "target": "python.org",
  "type": "domain",
  "verdict": "clean",
  "listedOn": 0,
  "listings": [],
  "ipsChecked": [
    {
      "ip": "188.166.95.178",
      "roles": [
        "mx",
        "spf"
      ],
      "source": "mail.python.org"
    }
  ],
  "listsChecked": [
    "psbl",
    "dronebl",
    "uceprotect-1"
  ],
  "auth": {
    "spf": {
      "status": "pass",
      "lookups": 8,
      "all": "~"
    },
    "dmarc": {
      "policy": "none",
      "valid": true
    },
    "dkim": {
      "selectorsFound": [
        {
          "selector": "google",
          "keyBits": 1024
        },
        {
          "selector": "k2",
          "keyBits": 2048
        }
      ],
      "selectorsChecked": 31
    },
    "notes": [
      "DMARC is p=none (monitoring only)."
    ]
  },
  "summary": "Not listed on 3 blocklist(s) checked for 2 IP(s) and the domain.",
  "chargedEvents": [
    "target-checked"
  ]
}

Lists that did not answer reliably appear in listsUnknown and are never counted as clean. Targets whose result is unknown are not charged (see Pricing).

Pricing

• $0.008 per target checked (domain or IP, including its MX/SPF IPs and the authentication summary)
• $0.01 per alert delivered
• $0.02 per AI plan

Targets whose result is unknown, invalid input and sample mode are never charged. Checking 100 domains costs $0.80. Daily monitoring of 10 domains costs about $2.40 a month.

FAQ

Why is Spamhaus off without a key? Spamhaus' free public mirrors are licensed for non-commercial use only, and they refuse queries from cloud resolvers. A paid tool using them would break both rules. Add your DQS key and Spamhaus ZEN and DBL are checked.

My result says "unknown" for a list. Why? That list refused or ignored queries from the resolver in use. Set your own resolver under "DNS resolvers", or add a keyed list.

Does it check my outbound IP when I use Gmail or Microsoft 365? It checks your MX IPs and any single IPs in your SPF record. Large providers' shared IPs are rarely the problem. With a dedicated sending IP, put it in SPF as ip4: or enter it as a target.

Limits

• Up to 1,000 targets per run and 12 IPs per domain by default (configurable up to 50).
• SPF ranges wider than /32 are not expanded.
• Domain-reputation lists (domain blocklists) are only available with a Spamhaus or Abusix key.
• The DKIM summary relies on common selector names; add your own selector if you use a custom one.

Sources & compliance

• Blocklist terms (read 2026-10-11):
  • PSBL https://psbl.org/howto/
  • DroneBL https://dronebl.org/docs/howtouse
  • UCEPROTECT licence https://www.uceprotect.net/en/index.php?m=13&s=0 and DNS usage https://www.uceprotect.net/en/index.php?m=6&s=11
  • Spamhaus fair use https://www.spamhaus.org/blocklists/dnsbl-fair-use-policy/
  • SpamRATS https://www.spamrats.com/lists.php
  • Abusix https://www.abusix.com/products/abusix-mail-intelligence/
  • SpamCop https://www.spamcop.net/bl.shtml
  • Mailspike https://mailspike.io/ip_verify
• Standards: RFC 5782 (DNS blocklists), RFC 7208 (SPF), RFC 7489 (DMARC), RFC 6376 (DKIM).
• Data and network: DNS lookups only, with no web scraping. Blocklist queries are capped per run and are well under the published per-day guidance.
• Security: blocklist keys and webhook URLs are secret inputs, redacted from every log line and output. Private, loopback and reserved IPs are never queried.
• UK GDPR / PECR: IP addresses can be personal data when they identify an individual's connection. Check IPs and domains you operate or are authorised to monitor. Email addresses are reduced to their domain; only the domain appears in the output.
• Blocklist results are third-party opinions provided "as is". Delisting decisions are made by each list operator.