Why Blocklists Make Us Better Email Marketers


For 2022, Webbula is launching a series of blog posts about email deliverability topics. We have a variety of esteemed authors from the email industry lined up to participate. 

  • Subscriber Management: How to Start, Maintain, and Break Up by Elizabeth Jacobi. Read it. 
  • Email Opt-Ins: It's All About Consent In the End by Matthew Vernhout. Read it here. 
  • Email Authentication 101: What It Is And Why It Is Important For Brand Reputation by Yanna-Torry Aspraki. Read it here. 
  • IP Warming- Do It Right or Do It Twice by Amanda Jackson. Read it.

Watch the discussion! 



Whether you are a seasoned veteran or new to email marketing, the term blocklist (aka blacklist) conjures up nightmarish stories about being outcasted with a scarlet letter of being a spammer and possibly drawing the ire of every deliverability professional and postmaster from every corner of the earth. However, let's be clear; every brand from every vertical, whether you are B2B or B2C, sending 400,000 or 40 billion emails, has fallen victim to being on a blocklist. You should treat being blocked like a badge of honor in that you and your program are human, and you made a mistake. You shouldn't be made to feel bad for being placed on a blocklist by any organization unless it is something that you consistently do that gets you to be blocked.

Over my 22 year career, I have learned a great deal from being on a few blocklists, and to be honest, it has made me a better email marketer.


A blocklist is a blacklist, and a blacklist is a blocklist. The terms have been used interchangeably for years across the email industry, but their meaning/action and how you got on them are the same. In recent years, the industry big dogs like Spamcop, Spamhaus, and Barracuda decided to use the term blocklist.

As of this writing, there are over 200 email blocklists out there, ranging from some dude living in his parent's basement with a zest for hating on all forms of email marketing and demands payment to an International Organization consisting of 38 people in 10 countries who work "to identify and pursue spam and malware sources around the globe." Out of the 200 blocklists, brands should only be concerned with about six of them as they are the ones that are highly regarded and regularly used by the ISPs. Let's be clear, anyone can start a blocklist, but it is the ones who are professionally maintained and updated are the ones that can have a significant impact on your success in getting your email delivered.


The short answer is that you get on a blocklist by sending spam, so don't do it. However, "sending spam" is too broad because our subscriber's definition of spam is much different from a marketer’s or someone in the C-Suite. As marketers, we have to take a collective step back and ask ourselves what risks we want to take with our program and then deal with the fallout should those risks backfire. You heard it correctly; YOUR actions in YOUR program determine whether or not you make it onto a blocklist. 

However, if we were to boil it down to three ways you get on a blocklist, it would be these:

  1. You hit a ton of the following spam traps. 
    1. Pristine: Email addresses that have never existed, so sending an email to them means you have bad data.
    2. Recycled: Old email addresses that have been converted, meaning that you are sending to someone that no longer has that email address. 
    3. Typo: gmial, yahooo, hotmial do not exist, so sending emails to typo addresses means you didn't spend the time cleaning and looking at your data.
  2. You send an email to a dirty list. A dirty list can be sourced either by your collection practices (sweeps, live events, giveaways, forms), shared or scraped lists, purchased lists, or excel sheets full of unknown sources but chock full of email addresses that came on a CD from five years ago. Dirty lists without a process to hygiene them is like fighting the heavyweight champion without training; you're going to get hit, and you might suffer some semi-permanent damage.
  3. You sprint out the gate with a ton of emails. If you have a new IP or domain that you are sending from, you will end up on a blocklist if you bolt out and start sending many emails and campaigns. It takes time for ISPs to trust your sending practices as they don't care who you are; they only care about what/who and how you send your emails.

A recommendation that I have made many times to clients worldwide is to assess the risks of who you send too regularly and make sure you are comfortable dealing with the fallout should you end up blocked. Talk to someone trusted in the industry around a warm-up, mitigation, and everything deliverability.


There are two types of blocklists; public and non-public.

A non-public blocklist example is that of Gmail or Yahoo blocklists, and since they prefer not to make them public, the only way you can tell is to analyze bounces regularly.

There are hundreds of public blocklists, but there are also two types; IP-based and Domain-based. Mailbox providers typically use IP-based to identify the IP addresses sending "spam." Domain-based, as the name implies, uses the senders' domain to create lists that they have associated with spam. In most cases, the domain isn't sending spam, but they utilize bad practices when sending email.

There is only a handful to be concerned about when it comes to the severity of public blocklists. These include Spamhaus, Spaxmcop, Barracuda, Proofpoint (they are behind blocking on Apple's mailboxes and more), and finally Invaluement

When dealing with Blocklists, here is a list of things that should throw a red flag to your organization when it comes to their legitimacy:

  • You should never have to pay to be delisted.
  • They list you for an unspecified reason, like a new domain registered.
  • They list just because your organization uses Google Workspaces.
  • They list or block you because your domain IP has a specific number. (no joke)
  • They don't have a way to contact them using email, but only on Twitter or some other form of digital communication that doesn't relate to email.


First things first, getting off a blocklist requires patience as it's not something that you can flip a switch and expect to be done in a matter of minutes. Second, the blocklist doesn't care WHO you are, just that you sent something that met their parameters to add you to the said blocklist. 

Most blocklist vendors will have a clear self-service path to delisting that will likely involve you giving them information about what potentially happened. The more you give, the better off you are when it comes to getting delisted quickly, so take the time to inquire about the listing, and by all means, if you can gain clarity from them on the what and why, it will help you track down if it was a specific mailing, domain or IP address. All of this is to learn, plan, and guide internally on future sends. Below are a few delisting links should you find yourself on one of the following blocklists


Being on a blocklist is neither fun nor transformative if you are an email marketer, it won't win you awards, and they are hard to explain to those who live outside the email world that things like this take time to solve. 

As professionals, we need to let other people who have a significant influence on our email programs know that our actions in the near and long term will determine how much blocklists will influence the outcome of our programs.

However, they make us better email marketers by teaching us that the fundamentals matter a lot for long-term success. They push us to become mindful and diligent in list management, acquisition, and hygiene. To some, being on blocklists is the fault of the ESP or system they use to send it, but in reality, the control remains with the organization itself. We can choose to be reckless and pay the price, or we can learn from our mistakes and make this industry a better place.

I challenge everyone who reads this post to elevate what and how we "do" email because it's the right thing to do, but it makes what we all do more satisfying.

Meet the Author

Andrew Kordek

Andrew is the VP of Customer Engagement at iPost, an advanced Email Service Provider (ESP) built for the Digital Marketer’s growing demands for data and hyper-personalization.  Prior to iPost, Andrew was the Co-Founder and Chief Strategist of Trendline Interactive where he led the email marketing strategy department. He has held client-side positions at Groupon, Sears, and Quest Software, where he was responsible for all aspects of their email marketing program, including strategy, execution, reporting, and analytics.

With over 20 years in the email marketing industry, he is a recognized innovator, thought leader, and advocate for responsible email marketing.

Andrew is an avid blogger, frequent speaker, and contributor to the email community.

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