Getting into the inbox, part four: Black Lists    |     Take a survey, earn 250 free send credits!

Email Deliverability Series, Part Four.

Getting into the inbox:
What you need to know about blacklists

Plus: How to find out if you are on one,
and how to get removed

In the ongoing battle against spam, email administrators use a combination of content filtering, whitelists and blacklists to keep spam out of their systems.

While few marketers know precisely what a blacklist is or how they might end up on one, most realize being blacklisted will negatively impact their email deliverability.

As a legitimate email sender trying to get your message through, it pays to understand how and why you might end up on a blacklist.

What is a blacklist?

A blacklist is a list of mail server IP addresses identified as actual or potential spam sources.

These lists, also known as blocklists, are managed by organizations and individuals determined to reduce or eliminate spam. ISPs and corporate mail managers use these lists as part of their spam prevention systems, essentially using them as a reference check before they accept email into their system.

Most mail systems do not even bounce (send back an undeliverable message) the email that is blacklisted, it simply disappears into the void and is never delivered.

How do you end up on a blacklist?

There are a handful of top blacklist organizations with a proven reputation to work hard to ensure the IP addresses on their list represent true spammers. These are the blacklists utilized by the major ISP's and corporations. The majority of blacklists however, are small operations, some poorly maintained, and thus not widely used.

Some of these organizations maintain spam trap addresses, which are usually posted discretely on the internet, but are otherwise unused. Any email sent to a spam trap address would have been harvested (automated software that scans web pages for email addresses) and is therefore most likely spam. Other lists are automated collections of IP addresses or blocks of IP address of open relay mail servers that might be compromised to send spam.

Some ISP's also maintain their own internal blacklists, so just because you are not on a public blacklist doesn't mean individual ISP's are not blocking your email. Usually this is due to a poorly configured email server (no reverse DNS or invalid message headers), sending to a lot of invalid addresses or having a percentage (usually relatively small) of spam or abuse complaints.

How do I avoid getting on a blacklist?

• Clean your list
  Take care to remove any bounced/undeliverable email addresses. You may also want to remove any info@ or webmaster@ addresses, or contact them for a direct email address instead.
  
  
• Use CAN-SPAM compliance footers
  Ensure your opt-out link works, and include the footer on ALL commercial email, whether to individuals, groups or lists
  
  
• Avoid spammy looking content and subject lines
  We've all seen spam, so make sure your email looks nothing like it. Use clear descriptive subject lines and dress the content or page format up enough so that your first impression is a positive one
  
  
• Use authentication and non-spoofed headers
  Adding a SPF record to your domain is a good idea, and never forge an email header to make the sender appear as-if it is coming from someone other than the actual source
  
  
• Never use email harvesters to build a list
  If you're grabbing random email addresses off the web, chances are you'll be caught in a spam trap, making it much harder to extract yourself from any resulting blacklisting
  
  
• Double check any list you purchase
  Most list sellers claim to be opt-in or double opt-in, but it should be obvious that they have not opted-in to receive email from you. It pays to make sure the names and addresses correspond to the email addresses (removing any that do not), and be sure to allow opt-out on all mailings to any purchased list
  

What if you ended up on a blacklist though no fault of your own?

Twice in the past year, we've had clients with deliverability problems related to blacklisting. In both cases it had nothing at all to do with email they had sent. They had ISPs who had assigned them recycled IP addresses. Unfortunately, whomever had those IP addresses years before had been using them for spam, and the blacklists didn't forget. In one case the ISP simply assigned a new IP address. In the other, the blacklist volunteer confirmed the information, and delisted the IP.

What do I do if I am on a blacklist?

It happens. And therefore most of the reputable blacklist organizations provide a removal process, so long as you can demonstrate that you are not a spammer.

You should regularly check your blacklist status.

The delisting process is different for each blacklist, but most provide an admin page, an email address, or a form to initiate the process. If you follow the delisting instructions, you will be able to resolve the issue. Many will require a copy of the message, a change to your list management practices if you have spam/abuse complaints, or at least clearing your list of any spam trap addresses (although they don't tell you what they are). You may need to provide proof of your changes.

So long as you are patient and professional, you should be able to get your IP off of the blacklist.

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How to check if your email domain is on a blacklist:

Before you can check to see if you are on a blacklist, first you need to know the IP address of your email server for your domain name. If you don't know this, type your domain name into this lookup tool.

Listed below are a couple of tools that allow you to check your IP against multiple blacklists:

MxToolBox

Take immediate action if you find yourself on any of these major blacklists:

• SpamHaus
  
  
• Mail Abuse Prevention System (MAPS)
  
  
• SpamCop Blocking List (SCBL)
  
  
• Spam and Open Relay Blocking System (SORBS)
  
  
• Composite Blocking List (CBL)
  
  
• NJABL.org
  
  
• Distributed Sender Blackhole Lists (DSBL)
  

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