For the complete site index, see llms.txt. Docs index: llms-docs.txt. Marketing corpus: llms-full.txt. Docs corpus: llms-full-docs.txt. Prefer markdown URLs where available (append .md).. Product skill: skill.md. Pricing: pricing.md. Docs MCP: /docs/mcp. Site MCP: /mcp.

Free tool — no account

Email Domain & IP Blocklist Checker

Query 50+ major global anti-spam DNSBL databases in real-time. Verify whether your sending domain or mail server IP is blacklisted, identify listing reasons, and get direct removal links.

Try sample:

Why checking global blocklists protects your reputation.

Being listed on major DNSBL databases causes mailbox providers like Gmail and Microsoft 365 to immediately reject or junk your outbound emails.

50+ Global DNSBL Networks

Spamhaus, Barracuda, SpamCop, and SORBS aggregate databases queried concurrently in real-time.

Zero-Latency Delist Links

Direct links to official removal forms so you can resolve false-positive listings immediately.

Automated MX & A Resolution

Enter a bare domain (e.g. yourcompany.com) and the tool automatically locates your mail server IP.

100% Stateless & Private

Searches are evaluated entirely in memory and discarded. No queries or domains are ever logged.

Automate blocklist checks via code.

Integrate real-time IP and domain reputation lookups into your CI/CD pipelines, staging environments, and monitoring alerts.

1

Install the Node.js package

npm install reloop-email
2

Check DNSBL blocklists with Node.js

check_blocklist.ts
1import Reloop from 'reloop-email';
2

3const reloop = new Reloop(process.env.RELOOP_API_KEY);
4

5const analysis = await reloop.tools.checkBlocklist({
6  target: 'reloop.sh',
7});
8

9console.log(`Clean: ${analysis.isClean} (${analysis.listedCount}/${analysis.totalChecked} listed)`);
10console.log('Results:', analysis.results);
3

Inspect JSON blocklist report (200 OK)

response.json
1{
2  "target": "reloop.sh",
3  "input_type": "domain",
4  "resolved_ip": "76.76.21.21",
5  "hostname": "reloop.sh",
6  "is_clean": true,
7  "total_checked": 20,
8  "listed_count": 0,
9  "clean_count": 20,
10  "scan_duration_ms": 340,
11  "results": [
12    {
13      "id": "spamhaus-zen",
14      "name": "Spamhaus ZEN",
15      "host": "zen.spamhaus.org",
16      "category": "reputation",
17      "is_listed": false,
18      "response_codes": [],
19      "response_time_ms": 85,
20      "delist_url": "https://check.spamhaus.org"
21    },
22    {
23      "id": "barracuda",
24      "name": "Barracuda BRBL",
25      "host": "b.barracudacentral.org",
26      "category": "spam",
27      "is_listed": false,
28      "response_codes": [],
29      "response_time_ms": 112,
30      "delist_url": "https://www.barracudacentral.org/rbl/removal-request"
31    }
32  ],
33  "recommendations": [
34    "Your sending IP and domain are clean across all tested global blocklists.",
35    "Maintain strict SPF, DKIM, and DMARC enforcement to preserve reputation."
36  ]
37}

Frequently asked questions.

Answers to common questions regarding email blacklists, DNSBL zones, and reputation recovery.

Ship your first email in minutes

Open-source, deliverability-focused, and yours to self-host or run on Reloop Cloud. No lock-in, no rewrite later.

Get started freeDocumentation
Reloop