Controls/EDCA-TLS-032.json

{
  "id": "EDCA-TLS-032",
  "title": "Edge recipient validation is enabled",
  "description": "The Edge Transport server MUST have recipient validation enabled in the recipient filter configuration. Without recipient validation, the Edge server accepts mail for non-existent recipients, consumes resources responding to directory harvest attacks, and delivers non-delivery reports that confirm valid addresses to external senders.",
  "verify": true,
  "subject": "Server",
  "category": "Transport Security",
  "severity": "Medium",
  "severityWeight": 6,
  "frameworks": [
    "Best Practice",
    "DISA"
  ],
  "references": [
    {
      "name": "Microsoft — Recipient filtering on Edge Transport servers",
      "url": "https://learn.microsoft.com/exchange/antispam-and-antimalware/antispam-protection/recipient-filtering"
    },
    {
      "name": "DISA STIG EX19-ED-000098: The Exchange Recipient Filter must block unaccepted domains (V-259620)",
      "url": "https://www.stigviewer.com/stigs/microsoft_exchange_2019_edge_server/2024-12-06/finding/V-259620"
    }
  ],
  "remediation": {
    "automatable": true,
    "description": "Enable recipient validation with Set-RecipientFilterConfig -RecipientValidationEnabled $true.",
    "scriptTemplate": "Set-RecipientFilterConfig -RecipientValidationEnabled $true"
  },
  "considerations": "Recipient validation requires an active Edge subscription so the Edge server holds a current copy of the recipient data. Enable the Edge subscription before enabling recipient validation.",
  "roles": [
    "Edge"
  ]
}