# List Hygiene (/guides/list-hygiene)

To protect your sender reputation, Bitelio keeps a constant eye on the bounce and complaint rates of the emails you send. Letting either rate climb hurts deliverability — and if it climbs far enough, it can result in your account being suspended.

## Bounce Management

An email bounces when it can't be delivered to the recipient's inbox. Every bounce is recorded on the contact as an `email.bounce` event, but automatic unsubscription happens **only on permanent (hard) bounces**. A transient (soft) bounce leaves the subscription untouched, since the upstream mail server usually retries delivery on its own.

### Types of Bounces

| Type                 | Description                                                                       | Auto-unsubscribes? |
| -------------------- | --------------------------------------------------------------------------------- | ------------------ |
| **Permanent (hard)** | Permanent delivery failure — invalid address, blocked domain, recipient rejected. | Yes                |
| **Transient (soft)** | Temporary delivery failure — mailbox full, server unavailable, greylisted.        | No                 |
| **Undetermined**     | The upstream provider couldn't classify the bounce.                               | No                 |

Every bounce, whatever its type, emits an `email.bounce` event that workflows and webhooks can react to — the payload's `bounceType` field tells you which kind you're dealing with.

### Preventing bounces

* [Verify email addresses](/api-reference/public-api/verifyEmail) at the point of signup, before they ever land on your list.
* Prune your list on a regular basis: pull unengaged contacts into a segment, then re-confirm or drop them.
* Use a workflow to build a confirmation flow — send a verification email and only mark the contact confirmed once they've clicked through.

## Complaint Management

A complaint is a recipient hitting the spam button on your email in their inbox provider. Whenever Bitelio is notified of one, the contact is **always automatically unsubscribed**, and an `email.complaint` event is recorded on them.

Mailbox providers weigh complaints far more heavily than bounces — even a modest complaint rate can drag down your sender reputation and deliverability.

### Preventing complaints

* Send content your audience actually finds relevant and useful.
* Every marketing email needs a clear, functional unsubscribe link — for `MARKETING` template and campaign types, Bitelio adds one automatically.
* Watch your sending frequency so contacts don't feel flooded.
* Only email people who genuinely opted in — never scraped, purchased, or long-stale lists.