Global Suppression List – Breathing New Life Into Your Contact Lists

A recent batch of improvements to dotdigital includes a new feature that you won’t actually see, but is going to be working furiously behind the scenes to ensure you get the best possible deliverability.

It’s time to get to know the Global Suppression List and understand how it will help everyone in the email ecosystem!

Here at dotdigital, we maintain a Global Suppression List (GSL), which is basically an amalgamation of all email addresses that have failed delivery for any reason (e.g. hard bouncing, those who mark campaigns as junk, etc).

This list is used when validating imports to ensure they contain ‘good’ data. If a list has a very high score (due to containing a lot of known bounced addresses, for example) then it’ll be blocked until you speak to our compliance team.

The reason we do this is simple – we believe it benefits everyone to keep the standards for email newsletters and distribution as high as possible. If dotdigital became just a proxy via which anyone could send any email they wanted without any verification, we’d suffer, you’d suffer and the billions of poor recipients out there would suffer.

We have such a mechanism to protect the entire email chain from these threats. But we’re about to make it an even more advanced and beneficial system.

Here’s how.

How are we making the Global Suppression List better?

Every time we detect that an email address is invalid, we add it to our GSL to help the GSL judge future imports better. It used to be that addresses that were added to the list stayed on there forever (barring a few cases). Think of it like the special machine they have in Ghostbusters that keeps the bad things at bay so society can continue to function!

But in last week’s update, we introduced a new feature that matches all user activity (e.g. clicks, opens) against our GSL. What this means is that we now check if anybody is on the GSL, marked as a bounced address, who should not be.

Email addresses can spring back to life from time to time and we wanted to make sure that we remove them from the GSL where appropriate. This update makes that a possibility and will kick in as an advantage for everyone’s list, immediately.


We’re pleased to report that based on a week’s activity, we only found 0.03% of user activity came from email addresses that we had previously flagged as bouncing. What this means is that actually the old Global Suppression List was doing its job very well.

So what was the point of putting all the work into this? Now we have a better understanding of the full picture. Call us perfectionists but we’re always going to be looking at where we can make improvements like this and how that will help our users. Even if it just verifies that the old systems were already doing a great job.

We are, of course, automatically re-activating these addresses (including removing them from your suppression list if they’re on there as a bounced address) and all users should see the benefits right away.

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