This is the second article in a multi-part introductory series on blacklists and blacklist activity.

At MxToolbox, our experts see the same story play out time and again:

For a few weeks or days, a small number of seemingly random emails bounce back or delivery fails.  At first, this is no real problem; email is never 100%, right?  Then, an important email to a big client goes missing and your users get nervous.  Administrators at your client’s organization says you’ve been blacklisted so they can’t accept email from you.  By then, you realize a large portion of your email isn’t getting through to anyone.  Your business is at risk and it’s all because you are on a blacklist!

Blacklist operators use a number of ways to catch and track undesirable activity but sometimes they capture legitimate businesses, like yours.  Typically, legitimate businesses get placed on a blacklist for one of the following reasons:

• Relaying spam through in-house email servers
• Sending malware, viruses or spam from individual accounts
• Denial of Service (DoS) or other type attacks from malware infected servers or networks
• Unknowingly Sending phishing emails or unsubscribe attacks
• Operating a mail server with no reverse DNS, such as from an IP address in your Internet Service Provider’s (ISP’s) dynamic IP address pool (DHCP)
• Failing to honor unsubscribes when mailing

So, you can see there are a number of reasons that you can end up on a blacklist without actually intending to do something undesirable.  Most often, our experts find that a blacklist issue was caused by your servers passing on spam, viruses or malware.  This condition is highly preventable!

At MxToolbox, our experts understand the common causes of blacklisting.  We can help you take immediate steps to get removed from blacklists and provide thoughtful solutions to keep you off blacklists in the future.  Contact us for more information.

In the next installment of our series on Blacklists, I will discuss some methods for preventing blacklists.

This is the first article in a multi-part introductory series on blacklists and blacklist activity.

A Realtime Blacklist, or RBL, is a list of IP addresses and domain names that an organization has decided to block, typically for spam.  There are many Blacklists, and each focuses on different types of undesirable behavior.  For example:

• CBL or Composite Blocking List is a DNS-based blackhole list of suspected e-mail services sending SPAM email resulting from virus or malware infections.
• Listing on Backscatterer blacklist indicates that your server is issuing “backscatter” in the form of Non-Delivery Reports (bounces) to external users, or misdirected autoresponders and sender callouts.
• Inclusion in either of the MAILSPIKE Blacklists (BL or Z) means that your IP Address has most likely been identified as being part of a real-time spam outbreak.

Blacklists are typically used to block undesirable internet traffic.  For example:

• Blocking access to websites on domains known for malware
• Blocking incoming email from IPs or domains known to be spammers
• Blocking access to IP addresses based in risky countries

MxToolbox does not own or operate any of these blacklists.  Instead, our email experts curate a list of over 100 blacklists and aggregate blacklist information into a single, central lookup tool.  Our tools enable you to check your mail server IPs and domain names against all these blacklists in a single consolidated interface.  Our monitoring packages enable you to monitor your domains and IP addresses for blacklist activity and get instant notification when placed on a blacklist.  We built our lookup and monitoring tools to help you navigate the complicated world of blacklists.

Your email deliverability depends on staying off of blacklists.  Get protected today.

In our next installment of our series on Blacklists, I will discuss how legitimate businesses sometimes end up on blacklists.