Information
This policy setting allows you to configure 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).
The recommended state for this setting is: 'Enabled'.
Rationale:
Incoming e-mails should be scanned by an antivirus solution such as Windows Defender Antivirus, as email attachments are a commonly used attack vector to infiltrate computers with malicious software.
Solution
To establish the recommended configuration via GP, set the following UI path to 'Enabled':
Computer Configuration\Policies\Administrative Templates\Windows Components\Windows Defender Antivirus\Scan\Turn on e-mail scanning
Note: This Group Policy path may not exist by default. It is provided by the Group Policy template 'WindowsDefender.admx/adml' that is included with the Microsoft Windows 8.1 & Server 2012 R2 Administrative Templates (or newer).
Impact:
E-mail scanning by Windows Defender Antivirus will be enabled.