The Mail Threat Protection component applies various groups of settings to protect mail. The settings groups are called email security levels. There are three email security levels: High, Recommended, and Low. The Recommended file security level is considered the optimal setting, and is recommended by Kaspersky.
To change the email security level:
The settings of the Mail Threat Protection component are displayed in the right part of the window.
After you configure a custom email security level, the name of the security level in the Security level section changes to Custom.