There are two settings available:
Project/Area Time Zone—this setting defines when a project “day” starts.
It affects the following functionality:
In case when project team is distributed across several locations in different time zones, this setting should be configured to a time zone with maximum number of team members in it.
Inbox email—an email address of Inbox list of a Project or an Area. All emails sent to this address will be transformed to tasks in the Inbox list. Currently the email address is displayed for informational purposes and cannot be modified.