Microsoft Defender AV must be configured to turn on e-mail scanning.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-213451	SRG-APP-000210	WNDF-AV-000027	SV-213451r823072_rule	2022-04-08	2

Description
This policy setting allows the configuration of e-mail scanning. When e-mail scanning is enabled, the engine will parse the mailbox and mail files according to their specific format in order to analyze the mail bodies and attachments. Several e-mail formats are currently supported, for example: pst (Outlook), dbx mbx mime (Outlook Express), binhex (Mac). If this setting is enabled, e-mail scanning will be enabled. If this setting is disabled or not configured, e-mail scanning will be disabled.

Description

This policy setting allows the configuration of e-mail scanning. When e-mail scanning is enabled, the engine will parse the mailbox and mail files according to their specific format in order to analyze the mail bodies and attachments. Several e-mail formats are currently supported, for example: pst (Outlook), dbx mbx mime (Outlook Express), binhex (Mac). If this setting is enabled, e-mail scanning will be enabled. If this setting is disabled or not configured, e-mail scanning will be disabled.

ℹ️ Check
Verify the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Scan >> "Turn on e-mail scanning" is set to "Enabled". Procedure: Use the Windows Registry Editor to navigate to the following key: HKLM\Software\Policies\Microsoft\Windows Defender\Scan Criteria: If the value "DisableEmailScanning" is REG_DWORD = 0, this is not a finding.

ℹ️ Check

Verify the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Scan >> "Turn on e-mail scanning" is set to "Enabled". Procedure: Use the Windows Registry Editor to navigate to the following key: HKLM\Software\Policies\Microsoft\Windows Defender\Scan Criteria: If the value "DisableEmailScanning" is REG_DWORD = 0, this is not a finding.

✔️ Fix
Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Scan >> "Turn on e-mail scanning" to "Enabled".