Our blacklist IP address checker  DNS-based anti-spam databases including Spamhaus, SORBS, NJABL, DSBL, and CBL to determine whether your current Internet connection is associated with spamming or unwanted online activity. The list of databases is updated regularly and reflects the most popular blacklists in use today. ISPs and web servers often look to these databases when deciding whether or not to block an IP address. If an IP address appears to be involved in spamming, the address will get added to one of these databases and may be blocked from receiving emails or using certain services.

How an IP address could be listed:

Most blacklisting is done automatically by sensors around the world that detect abnormal behaviour of Internet users and report it to their ISPs. These abnormal behaviours might include excessive failed login attempts to control panels, email accounts, site builders, SQL, SSH, FTP, etc in a short period of time or the download of copyright-violating files and other illicit activities. Some of these behaviours could also trigger a virus or malware infection on the device.

Some attackers work to avoid getting put on these blacklists by changing their IP addresses frequently and spoofing their identity with proxies or other tools. They might even create several different email addresses for their attacks and swap between them to prevent detection and avoid being delisted from a blacklist.