Documentation
Complete guide to setting up website monitoring with PingZen. API documentation, code examples, and best practices.
DNSBL Blacklist Monitoring
DNSBL (DNS-based Blackhole List) monitoring checks whether your mail server's IP address or domain is listed on spam blacklists. If your server gets blacklisted, your emails may land in spam folders or be rejected entirely. PingZen checks 50+ blacklists on a schedule and alerts you immediately if a listing is detected.
What Is DNSBL and Why Does It Matter?
DNSBL is a system used by email providers like Gmail, Outlook, and Yahoo to decide whether to accept or reject incoming emails. These providers check the sender's IP address against blacklist databases. If the IP is listed, the email is marked as spam or blocked.
Your mail server can end up on a blacklist for many reasons: a compromised account sending spam, misconfigured mail server, shared hosting with a bad neighbor, or even a sudden spike in email volume. The problem is often invisible — you keep sending emails, but recipients never see them.
Regular DNSBL monitoring catches listings early, before they damage your email reputation. The faster you detect a listing, the faster you can fix the root cause and request removal.
Who Needs DNSBL Monitoring?
- Any business that sends emails — newsletters, invoices, receipts, password resets
- Email marketing teams (Mailchimp, SendGrid, Amazon SES users)
- Companies running their own mail server (Postfix, Exchange, Zimbra)
- SaaS products that send transactional emails to customers
- Hosting providers and ISPs managing IP blocks
- E-commerce stores sending order confirmations and shipping notifications
How It Works
- Enter your mail server IP (e.g. 93.184.216.34) or domain (e.g. mail.example.com)
- PingZen automatically detects whether you entered an IP or domain
- On each check, PingZen queries 50+ blacklist providers via DNS
- If any blacklist returns a positive result, your server is listed
- Status changes to DOWN and you receive an alert with the list of blacklists
- When your IP/domain is removed from all lists, status returns to UP
What Gets Checked
PingZen checks your IP/domain against all major blacklist providers. Here are the most important ones:
Spamhaus ZEN
The most influential blacklist. Used by Gmail, Outlook, Yahoo. A Spamhaus listing can drop your email deliverability by 90% within hours.
Barracuda BRBL
Used by enterprise email gateways worldwide. Based on machine learning and millions of Barracuda devices.
SpamCop
Aggregates user spam complaints. A listing here means real people are reporting your emails as spam.
UCEPROTECT
Three levels: L1 (single IP), L2 (entire /24 subnet), L3 (entire AS). Escalating severity.
Configuration
Target
The IP address or domain of your mail server. Examples: 93.184.216.34, mail.example.com, smtp.yourcompany.com. PingZen auto-detects IP vs domain.
Check Interval
How often to check. For high-volume email senders: every 30-60 minutes. For standard business: every 6-12 hours. Minimum: every 60 seconds.
Alert Channels
Get notified via Telegram, Slack, Discord, email, webhook, or any other configured channel when a listing is detected.
Status Logic
Monitor status reflects your blacklist standing:
| Status | Meaning |
|---|---|
| UP | Not listed on any blacklist — your emails should be delivered normally |
| DOWN | Listed on one or more blacklists — your emails may be going to spam or getting rejected |
What to Do If You Get Listed
- Don't panic. Check the alert to see which blacklists flagged you.
- Identify the root cause: check for compromised accounts, misconfigured SPF/DKIM/DMARC, open relays, or unusual sending patterns.
- Fix the underlying issue. If an account was compromised, change passwords. If SPF/DKIM is missing, configure them.
- Request removal from each blacklist. Most have a self-service form (Spamhaus: 24-72h, Barracuda: 12-24h, SpamCop: auto-removes within 24-48h).
- After delisting, gradually resume normal email volume ("warm up") rather than sending a large batch immediately.
- Set up SPF + DKIM + DMARC if you haven't already — this is essential for email authentication.
Recommended Check Intervals
| Use Case | Interval |
|---|---|
| High-volume email sender (10K+ emails/day) | 30-60 minutes |
| Standard business email | 6-12 hours |
| Small business / personal domain | Once daily |
| Hosting provider / IP block monitoring | 1-2 hours |
Key Features
- 50+ blacklist providers checked on every scan
- Supports both IP addresses and domain names
- Auto-detection of IP vs domain — just paste your target
- Instant alerts via Telegram, Slack, Discord, email, webhook
- Detailed results: shows exactly which blacklists flagged you
- Custom DNSBL servers — add your own blacklist providers
- Automatic recovery alerts when you're delisted
Common Questions
What protocols can I monitor?
PingZen supports 23 protocols: HTTP/HTTPS, WebSocket (WS/WSS), TCP, UDP, ICMP Ping, gRPC, DNS, WHOIS, SSL certificates, Email (SMTP/IMAP/POP3), FTP/FTPS, DNSBL, PageSpeed, SOCKS5, MTProxy, API Check, and Transaction. You can monitor websites, APIs, servers, databases, and any network service.
How fast can I get alerts?
Telegram alerts are delivered within 1-2 seconds of detection. Slack and Discord notifications arrive almost instantly. You can configure multiple alert channels for redundancy.
Can I organize monitors by project?
Yes! PingZen supports workspaces, which let you organize monitors by project, environment, or team. Each workspace can have its own alert configurations and team members.
Is there an API for automation?
Absolutely. PingZen provides a full REST API with OpenAPI documentation. You can create, update, and delete monitors programmatically.
How do status pages work?
Status pages are public, branded pages showing your services' uptime. You can display real-time status and allow customers to subscribe for updates.
What happens if I reach my monitor limit?
We'll notify you when approaching your limit. You can pause some monitors or contact us for increased capacity. We never stop monitoring without warning, ensuring your critical services stay protected.
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