MXToolBox is a blacklist checker that tests a mail server IP address against over 100 DNS based email blacklists. You can enter either a server IP or domain name, and MXToolBox will instantly display a table with each blacklist in its database and its response. If everything is alright and your mail address isn’t blacklisted, you will see around 100 blacklist checks with “OK” next to them.
You can then instruct MXToolBox to monitor your mail address and alert you if it ever gets blacklisted. As a free user, you can monitor one mail address and access troubleshooting information about backlist, email, DNS, & web issues. To unlock more features, such as email delivery tracking, email performance monitoring, and real-time email reputation data, you need to purchase the Delivery Center service for $99 a month or $1,188 annually.
MXToolBox also offers an enhanced version of the Deliver Center service for $399 a month, called Deliver Center Plus. The enhanced version can process up to 5 million messages a month, and it includes alert integrations, advanced sender detail, and treat investigator.
DNSBL.info is a single place where you can check the blacklist status of your mail server's IP address on more than 100 DNS based blacklists. The service is owned and operated by CGP Holdings, a US-based company with 15+ years’ experience in developing dynamic content websites.
Performing a blacklist check on DNSBL.info is simple since all you need to do is enter the IP address you want to check into the Quick Blacklist Check field and click the Check This IP button next to it. What you want to see are green “OK” labels next to all blacklists checked by DNSBL.info.
DNSBL.info states that simply being listed does not always indicate the IP address is a source of spam. That’s because the blacklist checker takes into consideration many different criteria, some of which are based on the IP address' country or connection type. To verify the result, we recommend you use at least one other blacklist checker.
Multirbl.valli.org is a comprehensive blacklist email address checker that consults over 120 different email blacklist databases. The checker lets you perform FCrDNS and DNSBL lookups on IPv4/IPv6 addresses or domain names. All checks are performed extremely quickly, and you don’t need to spend any money to unlock everything Multirbl.valli.org has to offer because this blacklist checker is completely free.
If you would like to support it, you can send Bitcoins to its Bitcoin wallet, whose address can be found on the home page.