> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mailofly.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Email Suppressions

> How suppression lists protect your reputation from spam complaints and invalid addresses.

# Email Suppressions

The suppression list prevents your account from accidentally re-sending to addresses that have hard bounced, unsubscribed, or filed a spam complaint.

## Automatic Suppression

Mailofly automatically adds recipients to your organization suppression list when:

1. An address generates a permanent hard bounce (`5.1.1 User unknown`).
2. A recipient clicks an unsubscribe link.
3. A recipient files an abuse complaint through a feedback loop (Gmail, Yahoo, Outlook FBL).

Attempting to send to a suppressed address will immediately fail locally without damaging your external IP reputation.


## Related topics

- [Introduction](/sending/introduction.md)
- [Migration Guide](/audience/migration-guide.md)
- [Contacts](/audience/contacts.md)
- [Leaked API Keys](/guides/api-keys/leaked-api-keys.md)