Previously, we busted the myth on spam words, one of the great bogeymen of the email space.

But there remains one other haunt in the minds of email marketers everywhere— the IP blacklist.

Let’s be clear, blacklist/blocklists can have impacts on your email experience.

The myth in this case is to what degree of likelihood a sender’s current problems are due to a particular blacklist/blocklist.

Because the reality is – that is rarely the cause.

What is a blacklist vs blocklist?

As we jump into this topic, we need to make sure we’re on the same page concerning the differences between a “blacklist” and a “blocklist,” especially since a lot of blacklists call themselves blocklists. (I know, confusing)

A blacklist is a third-party tool or platform that lists senders due to abuse and suggests action being taken by users of their tool/platform against them within their own systems.

A blocklist is a tool within a receiving system/platform that follows a similar process of identifying abusive senders but its listing directly engages a block in the receiving system it is a part of.

The simplest difference is that one suggests blocking (blacklist) and another actually blocks the traffic directly (blocklist).

Many marketers see these as one and the same. If their IP is listed on a blacklist, they think that means they’re blocked.

That’s not the case most of the time.

What does it mean to be on a blacklist or blocklist?

Are you sending marketing mail? Then you’re on a blacklist somewhere. (Don’t believe me? Just pop in your domain or IP here)

Blacklists are a dime a dozen, and that’s because anyone on the internet can create a blacklist. There are actual blacklists that list you just for sending bulk mail regardless of the fact that your traffic is completely opted in.

Blacklists are most often unreliable because they are only able to use arbitrary identifier setups unless they have a connection with a larger receiving system.

Some regional blacklists have relationships with mailbox providers in their region and therefore have a stronger impact. For global, general traffic trends there are only a select few blacklists that have a larger impact (namely Spamhaus). These can cause delivery issues outright but are often used as one signal among many signals helping identify likely problematic traffic.

Blacklists have impressed themselves on email marketers because of the fear they induce. This was likely caused in the earlier eras of email when blacklists were the best attempt at identifying abusive senders before domain reputation really evolved.

Now, though, the real problem-causers between blacklists and blocklists are blocklists.

Getting on Gmail’s blocklist is a problem for your traffic there, and there’s no tool to check whether that’s the case or not. Or rather, no blocklist checking tool.

And funnily enough, it is entirely possible (and probable) that you won’t be listed on an impacting blacklist when you find yourself blocked by one of these providers.

That’s because the real, reliable data is found where the traffic patterns can be observed, and that’s with the mailbox providers themselves.

How to check if a listing is your problem

When it comes to either blacklists or blocklists, the usual identifier is a problem delivering to a particular provider (aka, bounce backs).

That means if you aren’t experiencing high bounce rates with a particular provider(s) then it is unlikely to be a blacklist/blocklist issue (there is always room for exceptions in deliverability, of course).

For a blacklist, it can be a bit more obfuscated but it tends to be for either more regional ISPs (France, Germany, etc.) or organizational mailbox providers (governmental, business addresses, etc.).

Likely you will see a spike in bounce rates for your campaigns, and it will be localized to one of these areas. Some mention the blacklist they referenced; some do not. You will likely need to work with a deliverability expert to utilize their specialized experience to help you remediate that.

For a blocklist, it tends to be a lot more direct and outlined in the bounce response.

Google, Microsoft, and many other larger providers with their own internal blocklists tend to include an alert concerning this block in their bounce-back responses.

The steps then are:

1. Check for high bounce rates

2. Check for a trend localized to particular mailbox providers (Gmail, Yahoo, Orange.fr, etc.)

3. Check for a trend in bounce-back errors advising of a block (“IP blocked”, etc.)

4. Check any provided links in the bounce-back responses for assistance in remediation

How to fix a blocklist/blacklist when it occurs

If you’ve done the above and you can’t find what is advised, then it is unlikely you have a block against you. I would advise using this write-up to help you troubleshoot the real source of your issue from here.

If you do discover or still suspect a blocklisting/blacklisting due to the above, then you’ll want to do the following:

1. Follow the instructions advised in the bounce responses (many will have links to resources)

2. Temporarily discontinue sending to subscribers at that particular provider if a majority are bouncing

3. Verify your signup forms are protected with CAPTCHA

4. Remove all subscribers who have not engaged in 12+ months

5. Remove any subscribers you do not have explicit permission to send to

6. Follow the remediation request process outlined in the resources

   1. If no process is outlined, work with your ESP’s deliverability team for remediating the issue

How to stay off blocklists

The key to staying off blocklists and blacklists is to keep your list squeaky clean.

To do this, you will want to do the following:

• Secure all signup sources with some form of CAPTCHA

• Make sure all signup sources are clear on what content is being opted in to

• Provide a highly visible unsubscribe link and Preference Center

• Consider utilizing Confirmed/Double opt-in

• Regularly re-engage and remove unengaged subscribers before they go a year without engagement

While the above will help remediate blacklist/blocklists, it can also assist with improving your overall engagements.

The key to avoiding many of the things that cause deliverability issues with email marketing is to build a marketing program focused on consent and relevant content.

Following the best practices that earn high engagements are also the practices that help protect against these types of deliverability issues.

Staying off of blocklists doesn’t have to be your focus. Do good work following best practices and this should take care of itself.