Using the Global Suppression List (GSL)


Using the GSL
Report definitions


The Global Suppression List (GSL) is a collection of known bad email addresses and domains including, ISP spam complainants.

You can use the GSL to cleanse your entire contact list by comparing your list of contacts against it. We'll automatically remove any known problem addresses, cutting down on the amount of complaints you might otherwise receive.

Using the GSL

Select Contacts > Suppressed contacts from the navigation bar. The next screen features five tabs.


Selecting the Global suppression list tab displays the following screen.


To execute this function, click on Run GSL

All of your contacts will be compared and the following report screen is displayed.


This screen details the amount of contacts found against the GSL and for what reason (the definitions are provided below). Use the checkboxes to deselect groups of contacts to suppress.

When ready, click on the Yes button and the selected groups will be unsubscribed. These contacts will then appear on your suppressed contacts list.


GSL suppression can’t be undone; recovery will take time and incur a cost

Once an email address has been suppressed using the GSL, it can't be undone. We implement this in the interests of email anti-abuse best practice, which takes into account constraints around suppressions and the serious impact of direct complaints on sending reputation.

If you have no option other than to request the reversal of email addresses suppressed via the GSL, you'll need to open a request with our support team. The removal process will include an initial analysis by our anti-abuse and compliance team to ensure there's no risk of reintroducing unsafe email addresses. Once cleared, our support team will then add the approved email address(es) back to your list. Due to the amount of time and effort required to complete this process, a cost will be incurred.

Report definitions

The report provides a number of reasons for the global suppression of email addresses and domains. Here are their definitions:

  • Known hard bounces: These are email addresses which have resulted in a hard bounce

    These email addresses are known to our system via internal machine learning and third-party data feeds.

  • Known ISP complainers: These are email recipients who've exhibited an unusually high number of ISP complaints. ISP complaints are caused by a recipient reporting received email to their inbox provider as a spam/junk message.

    When a recipient has decided to classify a message as spam/junk via their inbox provider's UI, they click the spam/junk button. This is considered a complaint. Several inbox providers allow visibility of this information through the employment of these feedback loops. Feedback loops allow our system to receive messages back from mailbox providers (MPs) about recipients who've complained.

    These recipients are known to our system through the application of complaint feedback loops (FBLs).

  • Known direct complainers: These are email recipients who've exhibited an unusually high number of direct abuse complaints. Direct complaints occur when recipients complain directly to us about a received message which they consider unsolicited (spam).

    Direct complainers may also use third party reporting methods such as, and other spam reporting organisations, including the Federal Trade Commission (FTC).

    These complaints are typically received via our abuse@ or postmaster@ email addresses. 

  • Invalid domains: These are domains that don't have a valid MX record and therefore can't receive email.  Additionally, an invalid domain could be what is known as a 'parked domain' - a domain which has been purchased, but not used for anything. Often, spam trap operators will set up MX records and report all received email as spam trap hits.

    These domains are known to our system via internal machine learning and third-party data feeds.

  • Known purchased addresses: These are email recipients who have appeared on known purchased email lists.
    Please note - although these recipients appear on purchased lists, they can often be legitimate email addresses who may have explicitly opted in to receive email. It's not uncommon to see several recipients on a legitimate, permission-based list which has never been contaminated with purchased, rented or appended data.
    These known purchased addresses are known to our system via a third-party data feed provided by a security company.

  • Known complainer: These are email recipients who've exhibited public anti-spam abuse complaints, typically through the use of popular social media platforms such as Facebook, Twitter and LinkedIn. They generally post public statements about receiving unsolicited mail from organisations on their social media profiles (public shaming).

    These recipients are known to our system via an external data feed provided by a third-party security company.

  • Known litigator: These are email recipients who are known to have entered into litigation with email senders over the receipt of unsolicited commercial email. A known litigator is a recipient who targets senders of commercial bulk email in an attempt to profit from the winnings of legal proceedings.

    These recipients are known to our system via a third-party data feed.
Have more questions? Submit a request


  • Avatar

    Hi there,

    Before I do this, I was wondering if there was a way to run this and be sent a visual report of those who are 'invalid domains' 'ISP complainers' etc? I would prefer to know the details of such contacts. 

    I don't want the contacts be moved into the overall GSL without me knowing who the contacts are before they get placed into the land of the unknown. Email address/name/date of suppression would be ideal.


    Is there an option for this?


    Many thanks

  • Avatar

    This page should make it clear that once you remove people using this tool, it can't be undone and you charge a fee to recover them.

  • Avatar

    Hi Reuben. Thanks very much for your suggestion. Further information covering this has now been added to the article.

    Edited by Neal Goldsmith