curl --request GET \
  --url https://app.sendmux.ai/api/v1/mailboxes/{public_id} \
  --header 'Authorization: Bearer <token>'

{
  "ok": true,
  "data": {
    "id": "mbx_clxxxxxxxxxxxxxxxxxxxxxxxxx",
    "email": "agent@acme.com",
    "display_name": "<string>",
    "quota_bytes": 123,
    "send_scope": {
      "type": "all",
      "provider_public_ids": [
        "<string>"
      ],
      "group_public_ids": [
        "<string>"
      ]
    },
    "status": "active",
    "created_at": "<string>"
  },
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  }
}