> ## 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.

# Use plus aliases

> Organize hosted inbox mail, send from aliases, and create alias-specific routines.

Add `+receipts`, `+newsletters`, or `+travel` to your hosted address to organize
mail without creating another inbox. For example, mail to
`myagent+receipts@mermail.app` arrives in the `myagent@mermail.app` mailbox.

> [!NOTE]
>
> Plus aliases are available when enabled for your hosted mailbox. They do not
> extend to custom-domain or connected inboxes. Aliases use your current hosted
> address; changing the mailbox address does not keep an old address active.

Valid aliases work without setup. They share the parent mailbox's storage,
permissions, sending limits, and billing. Saving an alias only creates a shortcut.

## Save and share an alias

1. Open your mailbox's **Settings**, then find **Aliases**.
2. Enter a tag such as `receipts` in **Alias tag**. Check the full-address preview.
3. Optionally enter a **Label**, then click **Save alias**.
4. Click **Copy address** and use that address with the service sending you mail.

Tags accept 1–32 letters, numbers, dots, underscores, or hyphens. Start and end
with a letter or number. Tags are normalized to lowercase. Do not include another
`+` separator. The complete address must also fit email address length limits.

## Find mail for an alias

Click **View mail** beside an alias to open its inbox filter. Incoming messages
with verified alias delivery information show an alias badge. You can also save
an observed alias from message details.

Filtering uses the actual delivery address, independently of visible **To** and
**Cc** headers. This supports Bcc delivery and avoids treating a spoofed To header
as proof that a message arrived through an alias. Older messages without verified
delivery information do not match an alias filter.

## Send and reply

New messages default to your primary address. In **From**, choose a saved alias
or enter another valid full alias address belonging to the same mailbox.

Replies default to the original delivery alias when verified information is
available, including AI-generated replies. Reply-all excludes your mailbox's own
alias addresses. Drafts and scheduled sends retain the selected sender.

If an alias is blocked before submission, sending stops with an error. Unblock
the alias or edit the sender before retrying; Mermail does not silently substitute
the primary address.

## Create an alias-specific routine

Click **Create routine** beside the alias. The editor opens with its recipient
alias constraint filled in. Complete the routine's instructions and other
conditions, then save it through the normal editor flow.

The `recipientAlias` constraint matches the normalized tag exactly against
verified delivery information. It must match even when other content conditions
use OR logic. Existing routines without this constraint continue to match as
before. Marketplace inboxes retain their automation restrictions.

## Block or unblock an alias

Click **Block** beside the alias and review the confirmation. Blocking:

* Discards future incoming mail to that alias.
* Stops sending from that alias, including pending scheduled sends.
* Keeps existing messages and routine settings.

Click **Unblock** to restore delivery and sending eligibility. Configured routines
can match future eligible deliveries again. Discarded mail is not restored.

**Remove shortcut** only removes the saved shortcut. It does not stop delivery or
remove an existing block. Use **Block** when you want mail to stop.

## Use the API or MCP

Use the [alias endpoints and MCP tools](/concepts/mailboxes.md#alias-apis-and-mcp)
to list, save, update, or remove shortcuts. Listing requires mailbox read access;
changes require mailbox settings administration permission.

For example, save a shortcut with the following request body:

```json theme={null}
{
  "tag": "receipts",
  "label": "Receipts"
}
```

Keep using the existing email `from` field for sending. Set it to the full address,
such as `myagent+receipts@mermail.app`. Saving the alias first is optional.

Authorized message responses can include `delivery_address`. Treat a null value
as unavailable delivery information; do not reconstruct it from To/Cc headers.

See [Mailboxes](/concepts/mailboxes.md#plus-aliases) for the API operations and
[Email module](/concepts/email.md) for delivery status and sending limits.


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