Email blacklisting happens when your IP or domain appears on a blocklist due to spam-like behavior or reputation issues. Learn causes, detection, and remediation.
Email blacklisting occurs when an IP address or domain is added to a blocklist (often called a DNSBL). Mail systems and filtering vendors use these lists to identify sources that may be sending spam, phishing, or unusually risky traffic.
A listing can happen for many reasons: sending to invalid addresses, high complaint rates, sudden volume spikes, compromised accounts, or poor list hygiene. Some lists are strict and automated; others are curated and require a manual delisting request.
If you’re listed, the first step is to stop the behavior that caused it, then follow delisting procedures for the relevant blocklist. Long term, focus on authentication, gradual sending, clean lists, and consistent engagement to rebuild reputation.