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

# Mailboxes

> Understand hosted and custom-domain mailboxes in Mermail.

A mailbox is the email identity your agent uses. It owns messages, folders, drafts, scheduled sends, notification settings, task triagers, and agent conversations.

## Address types

| Address type                  | Typical use                            | Provider path                                   |
| ----------------------------- | -------------------------------------- | ----------------------------------------------- |
| Hosted `@mermail.app` address | Fast setup and agent-owned inboxes     | Cloudflare Email Routing for inbound mail       |
| Custom subdomain address      | Team or product inboxes on your domain | Resend domain verification and provider routing |

Mermail prefers custom subdomains such as `support.mail.example.com` for custom-domain mailboxes. This avoids changing MX records for a root domain that may already run company email.

## Hosted mailbox rules

Hosted mailbox usernames:

* Must be 5 to 30 characters.
* Can include letters, numbers, dots, underscores, and hyphens.
* Cannot start or end with a separator.
* Cannot repeat separators.
* Cannot include reserved terms such as `admin`, `support`, `security`, or `mermail`.

## Mailbox data

Each mailbox can include:

* Messages and threads.
* System folders and user-created folders.
* Drafts, replies, forwards, and scheduled sends.
* Attachments.
* Agent conversations.
* Telegram and push notification settings.
* Task triagers for classifying and routing email.

## Related guides

<Card title="Create a mailbox" icon="plus" href="/guides/create-mailbox">
  Create a hosted mailbox or a mailbox under a verified custom subdomain.
</Card>