The emails notify you about files that are about to be unshared.
The frequency of the emails depends on how your organization's administrator has configured Tricent. By default, you receive a notification five, three and the day before the unsharing. Once unshared you get an email listing the files.
You don't have to do anything, if you are ok with the files being unshared. Tricent will just go ahead and unshare the files
It is only if you want to keep the sharing of a files that you need to react.
Read more about the process right here.