Suppression Lists

Suppression lists prevent Broadcast from sending emails to specific addresses. They are one of the most important tools for protecting your sender reputation and staying compliant with email regulations. This guide covers how suppressions work, how to manage them, and best practices for keeping your lists clean.

What Are Suppressions?

A suppression is a record that tells Broadcast: “Never send email to this address.” When an email address is on a suppression list, Broadcast will silently skip it during every send – broadcasts, sequence steps, and transactional emails alike. No error is raised, no bounce is generated, and the send simply does not happen.

Suppressions exist for several reasons:

  • Hard bounces – The email address does not exist or is permanently undeliverable
  • Spam complaints – The recipient marked your email as spam
  • Manual additions – You know an address should not receive email (e.g., a competitor, a known spam trap, or a request from the address owner)
  • Compliance – Regulatory requirements demand that certain addresses be excluded

Channel-Specific vs Global Suppressions

Broadcast supports two levels of suppression:

Global Suppressions

Global suppressions apply across every channel in your account. If you add an address to the global suppression list, that address will not receive email from any channel, regardless of their subscriber status.

Global suppressions are managed from Settings > Global Suppression. Use global suppressions for addresses that should never receive any email from your organization – for example, known spam traps, regulatory blocklists, or company-wide do-not-contact requests.

Channel-Specific Suppressions

Channel-specific suppressions only apply to the channel where they are created. The same address could be suppressed on one channel but still active on another.

Channel suppressions are useful when an address has delivery problems specific to one sending domain or when a subscriber has asked to stop receiving a particular type of content but remains subscribed to other channels.

Priority Order

When Broadcast checks whether to send an email, it evaluates suppressions in this order:

  1. Global suppressions are checked first. If the address is globally suppressed, the send is blocked regardless of channel settings.
  2. Channel suppressions are checked next. If the address is suppressed on the sending channel, the send is blocked.

If the address is not on either suppression list, the send proceeds normally (assuming the subscriber is active and not unsubscribed).

Adding Individual Suppressions

To add a single address to a suppression list:

  1. Navigate to Settings > Global Suppression (for global) or the channel’s suppression settings (for channel-specific)
  2. Click Add Suppression
  3. Enter the email address
  4. Choose the suppression type (bounce, complaint, or manual)
  5. Confirm

The address is suppressed immediately. Any scheduled broadcasts or pending sequence steps for that address will be skipped when they fire.

Bulk Upload

For larger suppression lists, you can upload addresses in bulk:

  1. Prepare a plain .txt file with one email address per line
  2. Navigate to the suppression list management page
  3. Click Upload or Bulk Add
  4. Select your file (up to 10,000 addresses per upload)
  5. Confirm the upload

Bulk uploads are processed in the background. You can continue working while the addresses are being added.

File Format

The file should be a simple text file with one email address per line:

[email protected]
[email protected]
[email protected]

No headers, no commas, no extra columns – just email addresses.

Managing Suppressions

Viewing and Searching

The suppression list page shows all suppressed addresses with their type (bounce, complaint, manual) and the date they were added. Use the search bar to quickly find a specific address.

Removing a Suppression

If an address was suppressed in error or the underlying issue has been resolved, you can remove it from the suppression list. Find the address and click the remove or delete option.

Removing a suppression does not automatically reactivate the corresponding subscriber. If the subscriber was also deactivated, you will need to reactivate them separately from their subscriber detail page.

Be cautious when removing suppressions. If an address was suppressed due to a hard bounce, sending to it again will likely result in another bounce, which can harm your sender reputation.

How Suppressions Work During Sending

Every time Broadcast prepares to send an email – whether it is a broadcast campaign, an automated sequence step, or a transactional API call – it checks the suppression lists before dispatching.

Here is what happens:

  1. Broadcast assembles the list of recipients for a send
  2. Each recipient’s email address is checked against the global suppression list
  3. Each recipient’s email address is checked against the channel suppression list
  4. Any suppressed addresses are silently removed from the send
  5. The remaining recipients receive the email normally

Suppressed sends are logged internally so you can see that the address was skipped, but no email is dispatched and no error is generated. This is by design – suppressions are meant to be invisible to the sending workflow.

For transactional emails sent via the API, the same check applies. If you call the API to send a transactional email to a suppressed address, the API will accept the request but the email will not be delivered.

Auto-Suppression from ESP Webhooks

One of the most powerful aspects of Broadcast’s suppression system is its integration with your email service provider’s webhooks. When your ESP reports a delivery event, Broadcast processes it automatically:

Hard Bounces

When an email permanently bounces (invalid address, domain doesn’t exist, mailbox full long-term), Broadcast:

  1. Records the bounce event
  2. Deactivates the subscriber so they stop receiving emails
  3. Adds the address to the channel’s suppression list

This prevents you from repeatedly sending to dead addresses, which is one of the fastest ways to damage your sender reputation.

Spam Complaints

When a recipient marks your email as spam (reported through feedback loops), Broadcast:

  1. Records the complaint event
  2. Deactivates the subscriber
  3. Adds the address to the channel’s suppression list

Complaint rates are closely watched by ISPs. Even a small number of complaints can land your sending domain on a blocklist. Automatic suppression on complaints is essential for maintaining good deliverability.

These automatic actions happen in real time as webhooks arrive. You do not need to take any manual action – Broadcast handles it for you.

Best Practices

Let auto-suppression do its job. The most important suppressions happen automatically through ESP webhooks. Make sure your webhook endpoints are properly configured for every email server you use. Without webhooks, Broadcast cannot react to bounces and complaints in real time.

Use global suppressions for organization-wide blocks. If an address should never receive email from any channel – such as a known spam trap, a legal request, or an internal test address – add it to the global suppression list rather than suppressing it on each channel individually.

Use channel suppressions for targeted blocks. If a delivery problem is specific to one channel’s sending domain or a subscriber has requested removal from only one type of communication, a channel-level suppression is more appropriate.

Be careful when removing suppressions. Before un-suppressing a bounced address, verify that the underlying issue has been resolved. Sending to an address that hard-bounced previously will almost certainly bounce again.

Review suppression lists periodically. Over time, suppression lists grow. Periodically review them to understand your bounce and complaint trends. A sudden spike in suppressions may indicate a list quality problem or a deliverability issue that needs attention.

Combine suppressions with list hygiene. Suppressions are a safety net, not a substitute for good list practices. Regularly clean your subscriber list, honor unsubscribes, and avoid purchasing email lists.

Troubleshooting

“I sent a broadcast but some subscribers didn’t receive it.”

Check the suppression lists. If a subscriber’s address is on either the global or channel suppression list, the email was silently skipped. View the broadcast’s delivery report to see which recipients were suppressed.

“A subscriber was suppressed but I didn’t add them.”

This is likely auto-suppression from an ESP webhook. Check the subscriber’s activity log for bounce or complaint events. The suppression was added automatically to protect your deliverability.

“I removed a suppression but the subscriber still isn’t receiving emails.”

Removing a suppression does not reactivate the subscriber. Go to the subscriber’s detail page and check their status. If they are inactive or unsubscribed, you will need to address that separately.

“How do I know if my webhooks are working?”

Navigate to your email server’s configuration page and check the webhook status. Most ESPs provide a way to send test webhook events. You can also check the activity log for recent bounce and complaint processing.

For more on subscriber management, see Managing Subscribers. To learn about connecting your email provider and configuring webhooks, visit the Email Servers documentation.