Mail filtering
Reject or quarantine traffic from IPs listed on reputation blocklists before it hits your MTA.
Intelligence API
Check Spamhaus, SpamCop, Barracuda, SORBS, and more in a single request. The Syndaq DNSBL API returns listed status, list count, and per-zone details as structured JSON.
At a glance
Use cases
Reject or quarantine traffic from IPs listed on reputation blocklists before it hits your MTA.
Challenge registrations from addresses already flagged by major abuse lists.
Triage complainants and open-proxy reports with a single multi-zone snapshot.
Attach blacklist status to security logs and SIEM events for faster review.
Integration
Subscribe to a DNSBL plan and copy your bl_sec_ secret key from the client area.
Pass any public IPv4 address by path or query parameter.
Use listed, list_count, and per-zone details to allow, challenge, or block.
Example
Every response includes a request_id for support correlation.
Rate limit and quota headers are returned on authenticated routes so you can backoff gracefully.
Authenticated with your Syndaq secret key over HTTPS. Private and reserved IPs return a clear error. DNSBL v1 supports IPv4.
curl -s "https://api.syndaq.com/v1/dnsbl/lookup/8.8.8.8" \
-H "Authorization: Bearer bl_sec_YOUR_SECRET_KEY"{
"success": true,
"ip": "8.8.8.8",
"cached": true,
"listed": false,
"list_count": 0,
"lists": [],
"checked": 8,
"request_id": "a1b2c3d4e5f6789012345678901234ab"
}Reference
Included with your Syndaq DNSBL plan.
| Method | Path | Description |
|---|---|---|
| GET | /v1/dnsbl/lookup |
Lookup blacklist status by ?ip= query parameter. |
| GET | /v1/dnsbl/lookup/{ip} |
Lookup blacklist status for an IP in the URL path. |
| GET | /v1/dnsbl/status |
Returns plan limits and quota for the authenticated key. |
Pricing
Transparent limits. Upgrade when your traffic grows—no surprise overages without a plan change.
Development and light production lookups.
Higher throughput for production apps.
High-volume lookups with priority limits.
FAQ
Pick a plan, create your keys in the client area, and start calling the API in minutes.
Choose a plan Ask a question