Receive an email when timesheet is submitted

Hello,

No, it is not possible, because it does not make sense that the Administrator receives that kind of email.

The administrator of your instance is supposed to be the person who makes the instance works perfectly and who tunes the rights access to each user. That person is not supposed to be responsible for the submission of the timesheet of the resources.

Timesheet and work time are actually important information for the project leader and the team manager to follow up their projects. That's why they are the persons who can receive such alerts and/or emails.
If they don't want to get emails, they can get only internal alerts (or none of them if they don't want to get the info at all).
 

Also, submission is different from filling-in the timesheet. Submission is supposed to occur only once a week.