Use the Global Suppression List to revise your contact list

Learn how to compare and revise your contacts against the global suppression list.


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 revise your entire contact list by comparing your list of contacts against it. We'll automatically remove any problematic addresses known to us, cutting down on the number of complaints you might otherwise receive. This does not clean all problems from your list. A good list acquisition is still key. 

Use the GSL to revise your contact list

  1. Go to Email > Contacts > Suppressed contacts.
  2. Select the tab Global suppression list.
  3. Select Run GSL. All of your contacts are compared to the GSL and, once complete, you see a report.
    The report shows the number of contacts found against the GSL and for what reason, you can see the definitions below. Use the check boxes to clear groups of contacts if you don't want to suppress them.
  4. When ready, select Yes. The selected groups will be unsubscribed. These contacts then appear on your suppressed contacts list.

GSL suppression can’t be undone; recovery takes time and incurs 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 that 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 an 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.
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