Blacklist Activity

Have you ever wondered which Blacklists are the most active?

At MxToolbox, we generate gigabytes of global blacklist activity data weekly from our public tool usage. This type of data is especially useful to determine when a blacklist goes does down or a dns service falls over and can relay that information to you. Like the rest of you, we use multiple monitors to let us know when an event occurs.

The most useful data we look at is the number of blacklists “Adds” (or listings) that occur.  A sharp/sudden spike or drop usually indicates a problem with a blacklist.

All Recent Blacklist Activity

Blacklist Activity

Top Activity By Blacklist

Blacklist Activity

You can see these charts on your free Dashboard and they are included in our free weekly Summary email.

As of 11/8/2013, these blacklists (below) have the most “adds” or listings by each respective blacklist operator. Each “add” or blacklisting is equivalent to one IP Address or one Domain being added to each list.


spamhaus-zen Activity


CBL Activity


Spamcop Activity


Barracuda Activity


As of 11/8/2013, the four blacklists that recently have the most listings are Spamhaus-ZEN, CBL (Spamhaus), Spamcop, and Barracuda. On average, these blacklist have generated the highest volume of listings for the last several years, and we do not expect that to change soon. SORBS and Lashback blacklists are usually close behind. IP Addresses and domains that make up these listings can be added by these blacklists for a variety of reasons such as spam and virus/malware infections. You can run a quick Blacklist Check on your domain name or IP Address here to make sure your IP Address or Domain are free of blacklist issues.