Ensure 'Nonexistent recipients' is set to 'True'

MediumLevel 1Manual reviewexchange

Description

This parameter is used to decide if messages whose recipient doesn't exist in the organization are blocked. When this parameter is set to $true, the Recipient Filter Agent blocks these messages. Note: The Set-RecipientFilterConfig cmdlet must be enabled Manual per the benchmark (recipient validation depends on EdgeSync/AD data on the Edge server). Run on each Edge Transport server.

How it is checked

Audit method: Manual review

This recommendation cannot be checked automatically. A scan lists it with these instructions when you pass --include-manual.

On the Edge Transport server run: Get-RecipientFilterConfig | Select Name, RecipientValidationEnabled. RecipientValidationEnabled must be True so messages to nonexistent recipients are rejected; also confirm EdgeSync replicates recipient data so validation works.

How it is fixed

Fix method: Guidance or infrastructure patch

Set-RecipientFilterConfig -RecipientValidationEnabled $true

Properties

Operating systems: Any
Tags: exchangeantispam
Reference: CIS Microsoft Exchange Server 2019 Benchmark v1.0.1 - 1.7 Ensure 'Nonexistent recipients' is set to 'True'