Exchange antimalware agent must be enabled and configured.

Microsoft Exchange 2019 offers built-in antimalware protection for messages going through the transport pipeline. When enabled, the default settings are configured to automatically update.

Exchange's built-in Malware Agent is not designed to address all malicious code protection workloads. This workload is best handled by third-party antivirus and intrusion prevention software.

Sites must use an approved DOD scanner. Exchange Malware software has a limited scanning capability and does not scan files that are downloaded, opened, or executed.

Open the Exchange Management Shell and run the following cmdlets:

Get-TransportAgent "Malware Agent"

If the identity "Malware Agent" is not set to "Enabled", this is a finding.

Open the Exchange Management Shell and run the following command:

& $env:ExchangeInstallPath\Scripts\Enable-AntimalwareScanning.ps1

This will automatically enable the anti-malware agent. After the script completes, run the following cmdlet to complete the process:

Restart-Service MSExchangeTransport

This may take up to 10 minutes to take effect.