What is IP Reputation?
IP reputation refers to the trustworthiness score assigned to an IP address based on its historical behavior. This score is maintained by various security organizations, email providers, and threat intelligence platforms. A clean IP reputation is essential for legitimate business operations, especially for email delivery, web hosting, and API services.
Important Warning
Poor IP reputation can result in emails being blocked, websites being flagged as malicious, and services being denied access to major platforms. Prevention is much easier than recovery.
Common Blocklists
There are numerous blocklists that track problematic IP addresses:
| Blocklist | Focus | Impact |
|---|---|---|
| Spamhaus | Spam, malware, botnets | Very High |
| SpamCop | Spam sources | High |
| Barracuda | General abuse | High |
| AbuseIPDB | All abuse types | Medium |
| SORBS | Spam, open relays | Medium |
Causes of Poor IP Reputation
- Spam: Sending unsolicited bulk email is the most common cause
- Malware Distribution: Hosting or spreading malicious software
- Phishing: Hosting phishing pages or sending phishing emails
- Botnet Activity: IP used as part of a botnet (C2 server or infected host)
- Port Scanning: Aggressive network scanning activities
- Brute Force Attacks: Password guessing attempts
- DDoS Participation: Being source or target of DDoS attacks
How to Check IP Reputation
Regularly monitor your IP addresses using these tools:
Recommended Tools
- MXToolbox: Comprehensive blocklist checker for email servers
- AbuseIPDB: Crowdsourced abuse database with confidence scores
- VirusTotal: Security vendors' verdicts on IP addresses
- Talos Intelligence: Cisco's threat intelligence platform
- ip4.market: Our built-in reputation checker in your dashboard
Best Practices for Clean Reputation
For Email Servers
- Implement SPF, DKIM, and DMARC authentication
- Use proper opt-in for mailing lists
- Monitor bounce rates and unsubscribes
- Never buy email lists
- Set up feedback loops with major email providers
For Web Hosting
- Keep all software updated and patched
- Use web application firewalls (WAF)
- Monitor for compromised accounts
- Implement DDoS protection
- Regularly scan for malware
For General Use
- Implement rate limiting on all services
- Use fail2ban or similar intrusion prevention
- Monitor outbound traffic for anomalies
- Have clear abuse policies and respond quickly to complaints
- Keep detailed logs for investigation
Recovering from Blocklisting
If your IP gets blocklisted, follow these steps:
- Identify the Cause: Determine what activity triggered the listing
- Stop the Abuse: Fix the underlying issue immediately
- Document Actions: Keep records of remediation steps taken
- Request Delisting: Submit removal requests to each blocklist
- Monitor: Continue monitoring to prevent recurrence
Delisting Times
Different blocklists have different delisting processes. Some are automatic after a period, others require manual requests. Spamhaus typically requires manual delisting with explanation of remediation.
IP Reputation and Leased IPs
When leasing IP addresses through our marketplace:
- We verify the reputation of all IPs before listing
- Each subnet has a reputation score visible in the marketplace
- IP holders are required to maintain clean reputation
- Lessees are responsible for maintaining reputation during the lease
- Severe abuse may result in lease termination