Symptoms
In an Exchange Server 2013 environment, when you run the Export-PublicFolderStatistics.ps1 cmdlet, it exports Russian (Cyrillic) characters as question marks (?).
Cause
This issue occurs because of unhandled Unicode characters.
Resolution
To fix this issue, install Cumulative Update 12 for Exchange Server 2013 or a later cumulative update for Exchange Server 2013.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
Learn about the terminology that Microsoft uses to describe software updates.