curl --request POST \
  --url http://localhost/public/v1/email/contacts/bulk-upsert \
  --header 'Content-Type: application/json' \
  --data '
{
  "contacts": [
    {
      "email": "[email protected]",
      "first_name": "<string>",
      "last_name": "<string>",
      "phone": "<string>",
      "foreign_id": "<string>",
      "country_code": "<string>",
      "custom_str_1": "<string>",
      "custom_str_2": "<string>",
      "custom_str_3": "<string>",
      "custom_str_4": "<string>",
      "custom_str_5": "<string>",
      "custom_int_1": 123,
      "custom_int_2": 123,
      "custom_int_3": 123,
      "custom_int_4": 123,
      "custom_int_5": 123,
      "custom_dec_1": 123,
      "custom_dec_2": 123,
      "custom_dec_3": 123,
      "custom_datetime_1": "2023-11-07T05:31:56Z",
      "custom_datetime_2": "2023-11-07T05:31:56Z",
      "custom_datetime_3": "2023-11-07T05:31:56Z",
      "custom_bool_1": true,
      "custom_bool_2": true,
      "custom_bool_3": true
    }
  ],
  "tags": [
    "<string>"
  ]
}
'

{
  "ok": true,
  "contacts": "<string>",
  "count": "<string>"
}