In Symantec Mail Security for Microsoft Exchange (SMSMSE) the option Trusted Domains or Users under Policies>Exceptions which allows you to exclude specific users generates an error when attempting to Deploy changes after adding a user containing a period before the @ symbol.
Trusted Domains or Users: At least one email or domain address should be specified. All the specified addresses must be valid.
We have created a hotfix to address this issue. Please download the attachment Symantec.Cmaf.UI.Core.dll.zip.
To apply the hotfix: