---
title: "Create an alias"
method: POST
path: "/mailboxes/aliases"
tags: ["Mailboxes"]
---

# Create an alias

`POST /mailboxes/aliases`

## Request

- Base URL: `https://api.poststack.dev`
- URL: `https://api.poststack.dev/mailboxes/aliases`
- Auth: one of:
  - HTTP bearer
  - OAuth 2
    - Authorization code: `https://poststack.dev/oauth/authorize`
    - Token URL: `https://poststack.dev/oauth/token`
- TypeScript: <https://skmtc.dev/poststack/apis/poststack-api/docs/mailboxes/aliases/post.ts> (a function with typed inputs; its response is checked against the schema)

## Request body

- CreateMailboxAliasInput
  - `domainId` union, required
    - string
    - integer
  - `localPart` string, required
  - `destinationMailboxId` string, required

## Response `201`

Created.

- object
  - `alias` MailboxAlias, required
    - `id` integer, required
    - `domainId` integer
    - `aliasAddress` string, required
    - `destinationMailboxId` integer, required
    - `createdAt` string, date-time

## Other responses

- `400`: Validation failed — `error` names each offending field (`field: message`).
- `401`: Missing, malformed or unknown credentials (`WWW-Authenticate: Bearer …` is set).
- `403`: The credential lacks the `mailboxes:manage` scope (body `{ error: "insufficient_scope", required, missing }`), or the team is suspended.
- `404`: Domain or destination mailbox not found.
- `409`: A mailbox or alias with this address already exists.
- `429`: Rate limited (10/min). `Retry-After` gives the seconds to wait; `X-RateLimit-*` headers are sent on every response.

## Changes

- **2026-09-30** `4dc1e20989c8`: 18 warning
  - added the new `daily_limit_exceeded` enum value to the `anyOf[#/components/schemas/Error]/code` response property for the response status `403`
  - added the new `daily_limit_exceeded` enum value to the `code` response property for the response status `400`
  - added the new `daily_limit_exceeded` enum value to the `code` response property for the response status `401`
  - added the new `daily_limit_exceeded` enum value to the `code` response property for the response status `404`
  - …14 more
- **2026-09-29** `ef5b22b98333`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/poststack/apis/poststack-api/changes/mailboxes/aliases/post.md)

---

[API](https://skmtc.dev/poststack/apis/poststack-api.md) - [All operations](https://skmtc.dev/poststack/apis/poststack-api/llms.txt) - [OpenAPI document](https://skmtc.dev/poststack/apis/poststack-api/revisions/0d3971e3a670?raw)