curl --request GET \
  --url https://api.hubapi.com/email/public/v1/smtpapi/tokens

[
  {
    "portalId": 123,
    "userName": "<string>",
    "emailCampaignId": 123,
    "createdAt": 123,
    "deleted": true,
    "createdBy": "<string>",
    "appId": 123,
    "campaignName": "<string>"
  }
]