curl --request GET \
  --url https://app.sendmux.ai/api/v1/mailbox/threads \
  --header 'Authorization: Bearer <token>'

{
  "meta": {
    "request_id": "req_clxxxxxxxxxxxxxxxxxxxxxxxxx"
  },
  "data": [
    {
      "id": "<string>",
      "subject": "<string>",
      "message_count": 123,
      "unread_count": 123,
      "has_attachments": true,
      "folder_ids": [
        "<string>"
      ],
      "participants": [
        {
          "email": "agent@example.com",
          "name": "Support"
        }
      ],
      "last_message": {
        "id": "<string>",
        "thread_id": "<string>",
        "folder_ids": [
          "<string>"
        ],
        "subject": "<string>",
        "preview": "<string>",
        "from": {
          "email": "agent@example.com",
          "name": "Support"
        },
        "to": [
          {
            "email": "agent@example.com",
            "name": "Support"
          }
        ],
        "cc": [
          {
            "email": "agent@example.com",
            "name": "Support"
          }
        ],
        "bcc": [
          {
            "email": "agent@example.com",
            "name": "Support"
          }
        ],
        "received_at": "<string>",
        "sent_at": "<string>",
        "size_bytes": 123,
        "has_attachments": true,
        "keywords": [
          "$seen",
          "$flagged",
          "agent_triaged"
        ],
        "flags": {
          "seen": true,
          "flagged": true,
          "draft": true,
          "answered": true
        }
      },
      "states": {
        "thread_state": "<string>",
        "email_state": "<string>"
      }
    }
  ],
  "pagination": {
    "has_more": true,
    "next_cursor": "<string>"
  }
}