Return Greylisting mail providers

Example response

{
  "data": {
    "autotrust_new_common_mail_providers": 1,
    "common_mail_providers": {
      "cpanel": {
        "autoupdate": 1,
        "display_name": "cPanel",
        "is_trusted": 1
      },
      "sectigo": {
        "autoupdate": 1,
        "display_name": "Comodo/Sectigo",
        "is_trusted": 1
      }
    }
  },
  "metadata": {
    "command": "cpgreylist_load_common_mail_providers_config",
    "reason": "OK",
    "result": 1,
    "version": 1
  }
}