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

# Suppressions and unsubscribe handling

> Learn how to use suppressions and unsubscribes to protect recipients and your domain reputation.

Suppression handling protects recipients and your domain reputation. Your application should decide when a recipient is
eligible for transactional mail, non-transactional mail, or no mail at all.

## Suppression types

MailChannels supports two suppression types:

| Type                | Use it for                                                                                                         |
| ------------------- | ------------------------------------------------------------------------------------------------------------------ |
| `transactional`     | Block all mail to a recipient when you should not send any message, including operational mail.                    |
| `non-transactional` | Block marketing, lifecycle, newsletter, or promotional mail while still allowing necessary transactional messages. |

If you create a suppression entry without `suppression_types`, the default is `non-transactional`.

## Suppression sources

Suppression entries can come from:

* `api`
* `unsubscribe_link`
* `list_unsubscribe`
* `hard_bounce`
* `spam_complaint`

Use the source to separate recipient preference, automated bounce handling, and manual administrative actions.

## Non-transactional messages

Set `transactional` to `false` for non-transactional sends. Non-transactional messages must be DKIM signed and must have
exactly one recipient per personalization. MailChannels adds unsubscribe headers for non-transactional messages.

<Warning>
  Do not mark marketing or promotional email as transactional to bypass suppression handling. That can create compliance
  risk and damage sender reputation.
</Warning>

## Operational workflow

1. Import existing unsubscribes and hard bounces into the suppression list before cutover.
2. Store `hard-bounced`, `complained`, `unsubscribed`, and unsubscribe-related webhook events.
3. Update your application preference store from those events.
4. Check your own preference store before calling MailChannels.
5. Review suppression list entries by recipient or source when debugging.