Проверяйте почтовый домен перед регистрацией

$ curl https://api.authguard.ru/v1/check/email \
  -H "Authorization: Bearer ag_live_xxx" \
  -d '{"email":"user@company.ru"}'

{
  "decision": "block",
  "risk_level": "high",
  "email_domain": "company.ru",
  "detected_provider": {
    "name": "Google Workspace",
    "jurisdiction": "foreign"
  },
  "evidence": {
    "mx_records": ["aspmx.l.google.com"]
  }
}