curl --request GET \
  --url https://api.hubapi.com/marketing/v3/transactional/smtp-tokens \
  --header 'Authorization: Bearer <token>'

{
  "paging": {
    "next": {
      "after": "<string>",
      "link": "<string>"
    }
  },
  "results": [
    {
      "campaignName": "<string>",
      "createContact": true,
      "createdAt": "2023-11-07T05:31:56Z",
      "createdBy": "<string>",
      "emailCampaignId": "<string>",
      "id": "<string>",
      "password": "<string>"
    }
  ]
}