IP-Tests / Blacklist Test

The blacklist test will check your mail server's IP address against multiple DNS based email spam blacklists. If your mail server has been blacklisted as spammer, probably some of your email messages may not be delivered to your recipients. Email blacklists (also known as DNSBL - DNS-based blackhole lists or RBL - real-time blackhole lists) are a common way of reducing spam and are used as live DNS zones that can be queried in real-time by the mail servers.

A DNS-based Blackhole List (DNSBL) or Real-time Blackhole List (RBL) is a list of IP addresses published through the Internet Domain Name Service (DNS) either as a zone file that can be used by DNS server software, or as a live DNS zone that can be queried in real-time. DNSBLs are most often used to publish the addresses of computers or networks linked to spamming; most mail server software can be configured to reject or flag messages which have been sent from a site listed on one or more such lists. The term "Blackhole List" is sometimes interchanged with the term "blacklist" and "blocklist". A DNSBL is a software mechanism, rather than a specific list or policy. There are dozens of DNSBLs in existence, which use a wide array of criteria for listing and delisting of addresses. These may include listing the addresses of zombie computers or other machines being used to send spam, listing the addresses of ISPs who willingly host spammers, or listing addresses which have sent spam to a honeypot system.

If you are listed with a DNSBL you should first correct the problem causing the listing of your ip and then visit the DNSBL's website directly for more information.