Information
This policy setting controls whether e-mail messages dragged from Outlook to the file system are saved in Unicode or ANSI format.
If you enable this policy setting, when users drag an e-mail message from Outlook to the file system, Outlook uses the Unicode character encoding standard to create the message file, which preserves special characters in the message.
If you disable or do not configure this policy setting, when users drag an e-mail message from Outlook to the file system, the message file created is in ANSI format. The recommended state for this setting is: Disabled.
Rationale:
By default, when users drag e-mail messages from Outlook to a Windows Explorer window or to their Desktop, Outlook creates a .msg file using the native character encoding format for the configured locale (the so-called 'ANSI' format). If this setting is Enabled, Outlook uses the Unicode character encoding standard to create the message file, which preserves special characters in the message.
However, Unicode text is vulnerable to homograph attacks, in which characters are replaced by different but similar-looking characters. For example, the Cyrillic letter ? (U+0430) appears identical to the Latin letter a (U+0061) in many typefaces, but is actually a different character. Homographs can be used in 'phishing' attacks to convince victims to visit fraudulent Web sites and enter sensitive information.
Solution
To implement the recommended configuration state, set the following Group Policy setting to Disabled.
User Configuration\Administrative Templates\Microsoft Outlook 2016\Outlook Options\Other\Advanced\Use Unicode format when dragging e-mail message to file system
Impact:
Disabling this setting enforces the default configuration in Outlook, and is therefore unlikely to cause significant usability issues for most users.