A blacklist check searches anti-spam databases to see if an IP address is blocked from sending emails. It can be done by the domain owner or a monitoring company, and can help identify why an IP is blocked, even if it’s not a source of spam.
A blacklist check is a comprehensive search of several anti-spam databases to determine if a particular IP address has been blacklisted. Anti-spam databases, or blacklists, are a common method of preventing the delivery of spam email messages. The lists consist of IP addresses that are known or thought to be sources of spam. All blacklisted IP addresses cannot send emails.
No alerts are sent when an IP address is added to an antispam database. For this reason a blacklist check is often the only way a domain owner can be notified of inclusion in the blacklist database. Some lists may be permanent, while some databases put expiration dates on blacklisted addresses.
There are dozens of antispam databases. A blacklist check mainly consists of a search of these databases for a particular IP address. To perform blacklist checking, the IP address of a remote mail server is converted into a domain name, using the ip4r format. That name is then entered into the search box for each database. Once the search is complete, a list is then compiled of the databases where the IP address in question is blocked by the individual who performed the search.
A blacklist check can be performed by the individual domain owner on a blacklist search site or by a company that offers blacklist monitoring services. There are several websites that do blacklist checks. Some of these are free, while others have a monthly fee. Many of the paid sites offer free trials. Companies that provide daily blacklist monitoring typically offer services for a monthly fee.
Inclusion in a blacklist database means that your mail server is blocked by DNS-based Blackhole List (DNSBL) filters. Not all domains associated with a banned IP address are sources of spam. A blacklist check gives a domain owner the ability to research why a particular IP is not sending messages.
A domain can be blocked simply because its IP address hosts known spammers. In other cases, a spammer may have infected a machine without its owner’s knowledge so that it automatically sends unsolicited email. A misconfigured mail server sending incorrect information could also lead to inclusion in a blacklist database.
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