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The suppression list is an automated safeguard that helps maintain your email list hygiene and protect your sender reputation. When using OneSignal as your email service provider, this feature automatically manages problematic email addresses to prevent deliverability issues. See Email deliverability for more details.

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How it works

When OneSignal detects any of the following conditions:
  • An email recipient marks your message as spam
  • An email address produces a hard bounce (permanent delivery failure)
The system automatically adds these email addresses to your suppression list. Once an address is suppressed, OneSignal no longer sends emails to it, helping to:
  • Maintain a clean email list
  • Improve overall deliverability
  • Protect your sender reputation
  • Reduce bounce rates

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Managing your suppression list

You can view and manage your suppression list by navigating to Settings > Email > Suppression:
Suppression list in the OneSignal dashboard showing suppressed email addresses
Here you can find a list of all suppressed email addresses, separated into tabs depending on whether they were the result of a bounce, spam report, added manually through the dashboard, or uploaded via the CSV Import tool.
Use the Reported as spam tab to spot patterns by inbox provider. For example, if you see a high concentration of Outlook, Hotmail, or Live addresses reporting spam, that indicates poor sender reputation with Microsoft-owned inboxes. Review your consent and opt-in practices to ensure users are explicitly consenting to receive email. See Email reputation best practices for guidance on improving your sender reputation.
If you are using another ESP as your email service provider, your suppression list must be managed directly through your ESP’s platform.

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Adding new suppressions

To manually add a new email address to your suppression list, click the Add Email button:
Add Email button in the OneSignal suppression list
To add email addresses in bulk, click the Import buttons to use the CSV Import tool. In the CSV, include a suppressed column with the value set to true for each email address row you want in the suppression list.
Example CSV
email,suppressed
test@example.com,true
Map this column to suppressed after uploading your CSV:
CSV import tool with suppressed column mapped for bulk suppression

Import CSV tool

Learn how to import email addresses in bulk using the CSV Import tool.

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Removing suppressions

To remove a suppression, click the trash icon next to the email address:
Removing an address from the suppression list allows OneSignal to send emails to it again. If the address was suppressed due to a hard bounce, re-sending to it may result in another bounce and can harm your sender reputation. Only unsuppress addresses you have confirmed are valid and able to receive email.
To remove emails in bulk, use the CSV Import tool and include a suppressed column with the value set to false for each email you want to unsuppress. Map this column to suppressed after uploading your CSV.

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FAQ

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What triggers an automatic suppression?

OneSignal automatically suppresses an email address when a recipient marks your message as spam or when the address produces a hard bounce (permanent delivery failure). Soft bounces (temporary failures) are not automatically suppressed.

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Does removing a suppression re-subscribe the user?

Removing an address from the suppression list allows OneSignal to send to it again, but it does not change the user’s subscription status. If the user previously unsubscribed, you must also update their subscription separately.

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Are suppressions per-app or account-wide?

Suppressions are per-app. Each OneSignal app maintains its own suppression list. An email address suppressed in one app is not automatically suppressed in another.

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What if I am using SendGrid, Mailchimp, or Mailgun directly?

The OneSignal suppression list only applies when OneSignal is your email service provider. If you are sending email through a third-party ESP like SendGrid, Mailchimp, or Mailgun, your suppression list must be managed directly through that provider’s platform. OneSignal does not sync suppression data with external ESPs.

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Can I manage suppressions via the API?

You can add or remove suppressions in bulk using the CSV Import tool. For individual suppression management via API, use the Create User or Update Subscription endpoints.

Email deliverability

Key concepts like reputation, bounces, spam traps, and inbox placement.

Email reputation best practices

Warm-up schedules, opt-in strategies, sunset policies, and more.

CSV import

Import and manage user data including suppressions in bulk.