curl --request GET \
  --url https://api.hubapi.com/marketing/v3/emails/statistics/list \
  --header 'Authorization: Bearer <token>'

{
  "emails": [
    123
  ],
  "campaignAggregations": {},
  "aggregate": {
    "deviceBreakdown": {},
    "qualifierStats": {},
    "counters": {},
    "ratios": {}
  }
}