Guide

Spamhaus XBL

What is Spamhaus XBL?

Spamhaus XBL is a real-time IP blacklist. Being listed on XBL indicates that your IP address has existing security vulnerabilities, such as malware infection, unauthorized hacker takeover, or open proxy services. These issues cause your IP to send out malicious network traffic and spam emails without your awareness.

Reasons for IP Being Listed on XBL Compromised server:

  • The server is implanted with Trojans or malicious bulk email-sending programs.
  • Open proxy/relay abuse: Improperly configured proxy servers or mail servers are exploited by external attackers.
  • Infected devices within the local network: Other office devices on the same LAN are infected with botnet viruses and initiate malicious outbound traffic.

Mitigation Process

You must fully resolve all security flaws before applying for delisting. Otherwise, the IP will be relisted immediately, and your appeal privileges may be permanently restricted.

  • Stop outbound traffic: Immediately suspend all outbound email queues from this IP.
  • Security audit Inspect abnormal running processes on the server. Use network monitoring tools including Linux netstat and Windows Tcpview to detect unusual outbound connections targeting external SMTP Port 25.
  • Optimize firewall rules: Restrict firewall access and only permit trusted internal mail server IPs to connect to external Port 25.
  • Clean threats & reinforce security: Remove all malicious programs, update operating system patches and all CMS platforms as well as plugins, reset all SSH and FTP login passwords, and enable two-factor authentication (2FA).

Official Delisting Process

  1. Visit the official Spamhaus lookup center: https://check.spamhaus.org
  2. Enter the blocked IP address to view detailed XBL violation details.
  3. After confirming all vulnerabilities are fixed, click Self-Service Delisting at the bottom of the page to submit an unblock request.
  4. Fill in the application form with a corporate domain-bound email address instead of free public mailboxes such as Gmail.
  5. State clearly in the description: We have fully investigated and fixed all security vulnerabilities, closed abnormal ports and completed full system updates.