An email blacklist, also called DNSBL, or DNS-based Blackhole List, a Block List, or a Blacklist, is a list of IP addresses that are published through the Internet Domain Name Service. Blacklists are often used to publish the IP addresses of networks or computers that are linked to spamming. Note that mail server software programs can be configured to flag or reject messages sent from sites that are listed on such blacklists. There are over one hundred DNS blacklists that are in service today. Internet Service Providers or ISPs and Email Service Providers use blacklists to control spam to determine if emails should be accepted by their servers. If the IP address of your computer or mail server is blacklisted, about ½ the people you send emails to will not receive them. You should use an IP address blacklist monitor to monitor and keep track of your IP address against popular blacklists. This is important because you will then be able to take the necessary actions to remove your IP addresses from such blacklists. Other than notifying you whenever you get blacklisted, an IP address blacklist monitor will generate weekly reports that will keep you informed on the status of your IP address. Keeping track of blacklisting is advantageous in that your business will not suffer. You will get the latest blacklisting and PTR (Reverse DNS) status of your IP addresses, delisting information, your blacklisting and delisting history, and PTR records history of your IP addresses. An IP address blacklist monitor is basically a service that notifies you whenever you are blacklisted and that helps you in the process of delisting. Note that these services are not blacklists and they are not affiliated with blacklists. The first step in monitoring is signing up with a service. After signing up, enter the IP address of the mail server (SMTP) you use to send emails. There are also other ways of finding your IP address. So, how do you delist after your IP address blacklist monitor shows that you are blacklisted? You must first resolve the original cause of the blacklisting. This could be the removal of malicious software, configuring your mail server properly, or deactivating a spammer hosting account. Note that some blacklists will detect this change and remove your IP address from their database automatically following positive results from an IP address blacklist monitor, but you might be required to request for delisting from others. Different blacklists have different procedures for doing this and they are available in the blacklist maintainer website. The two types of blacklists that your IP address blacklist monitor will be useful for are realtime blacklist DNS (RBLDNS) and right hand side domain, or RHSBL blacklists. You can do bulk IP address blacklist monitoring. Note that while a DNSBL can be a powerful tool to stem the flow of spam, false positives that result in the flagging as spam of legitimate email, and the rejection by mail servers do occur occasionally. You could get an IP address blacklist monitor that is free of charge. An average IP address blacklist monitor will check your IP address for blacklisting every 4 hours. To increase your email delivery rate, consider other network tools such as PING and traceroute.