Hi Dennis,
Yes, you can override the language file to customize the email subject and body.
Please first see this article:
How to override resource files of FileVistaThe language strings you need to customize are the following:
<String key="666">{0} Event Notification - {1}</String>
<String key="667">An event has occured in a folder that you ({0}) were set to receive notifications from. The event details are listed below.</String>