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

# Mailboxes

> Create mailboxes, manage passwords, set sender identity, and control inbound sender rules.

A mailbox is one email address on a verified sending & receiving custom domain or on the shared `myagent.mx` domain. It can send mail, receive mail, hold messages, and have its own passwords and sender rules.

<Note>
  Each team starts with **50 active mailboxes**. See [Team
  limits](/docs/guides/team-limits).
</Note>

## Create a mailbox

<Steps>
  <Step title="Open Mailboxes">
    Open **Mailboxes** and select **Create mailbox**.
  </Step>

  <Step title="Choose the address">
    Enter a local part and choose a verified sending & receiving domain. Leave
    the local part blank if you want Sendmux to generate one.
  </Step>

  <Step title="Set display name and storage">
    Add an optional display name and choose **1 GB**, **5 GB**, or **50 GB**
    storage.
  </Step>

  <Step title="Save the password">
    Copy the mailbox password when it appears. It is shown once.
  </Step>
</Steps>

## Mailbox passwords

Create one password per device, app, or integration. That makes revocation safer because you can remove one password without breaking every other connection.

Mailbox passwords can be used for:

* Sending through SMTP.
* Authenticating mailbox-scoped API calls.
* Connecting a mail client to the mailbox.

Use **New password** on the mailbox detail page to create another password. Use **Revoke** to disable one immediately.

## Send from a mailbox

Use a mailbox password as the SMTP password or as the bearer token for the
[Sending API](/docs/guides/sending-via-http). For mailbox-style workflows, call
`POST /mailbox/messages/send` through the [Mailbox API](/docs/mailbox-api/introduction)
to send as the authenticated mailbox and track its submissions.

## Sender identity

Open a mailbox and choose **Edit sender identity** to set:

* Sender name.
* Plain text signature.
* HTML signature.

These values become the mailbox defaults. Individual API sends can still provide their own message fields.

## Sender rules

Sender rules control inbound mail for the mailbox. Open a mailbox and use the **Sender rules** card to add rules, then choose **Save rules**.

| Rule type | Behaviour                                                              |
| --------- | ---------------------------------------------------------------------- |
| **Allow** | Deliver only mail that matches a rule. Every other sender is rejected. |
| **Block** | Reject mail that matches a rule. Every other sender is delivered.      |

A mailbox can use allow rules or block rules, not both at the same time. Clear all rules before switching rule type. Removing every rule turns filtering off, so all senders are delivered again.

### Pattern formats

Each rule matches the sender's envelope address. Three formats are accepted:

| Pattern            | Matches                                               |
| ------------------ | ----------------------------------------------------- |
| `name@example.com` | That exact address only.                              |
| `example.com`      | Every address at that domain.                         |
| `*@example.com`    | Saved as `example.com` — every address at the domain. |

Patterns are case-insensitive and stored in lowercase. Each rule can carry an optional note (up to 255 characters) to record why it exists — notes never affect matching. A mailbox or domain can hold up to 1,000 rules.

### How matching works

* Rules run before a message is accepted, so a blocked sender receives a rejection from their own provider rather than landing in spam. Rejected mail is not billed as accepted inbound usage.
* Mailbox rules take precedence: when a mailbox has its own rules, any domain-wide rules are skipped for that mailbox.
* If a rule can't be saved, the editor shows the reason inline — fix the highlighted pattern and save again.

### Manage rules via the API

The Management API exposes the same rules for automation: `GET`/`PUT /mailboxes/{public_id}/filters` for one mailbox, and `GET`/`PUT /domains/{public_id}/filters` to apply a rule set across every mailbox on a sending & receiving domain. Each `PUT` replaces the whole rule set in a single atomic operation. See the [Management API reference](/docs/api/introduction).

## Suspend, resume, and delete

* **Suspend** pauses inbound mail, outbound sends, mailbox API access, IMAP, and SMTP without deleting messages, passwords, or settings.
* **Resume** restores mailbox access and sending from the mailbox address.
* **Delete** removes the mailbox, its messages, API keys, and passwords.

## Related guides

<Columns cols={2}>
  <Card title="Domains" icon="globe" href="/docs/guides/domain-management">
    Verify sending & receiving domains before creating branded mailboxes.
  </Card>

  <Card title="API keys" icon="key" href="/docs/guides/api-keys">
    Create mailbox keys for API and mail client access.
  </Card>

  <Card title="Push delivery" icon="radio" href="/docs/guides/mailbox-push-delivery">
    Choose between polling, realtime events, webhooks, and the coming-soon push
    URL.
  </Card>

  <Card title="Webhooks" icon="webhook" href="/docs/guides/webhooks-setup">
    Receive inbound and delivery events at your HTTPS endpoint.
  </Card>

  <Card title="Mailbox API" icon="mailbox" href="/docs/mailbox-api/introduction#event-stream">
    Stream live received-message events from a mailbox key.
  </Card>
</Columns>