Talent Community Email Alerts - what jobs are pulled into the List of Requisitions

Summary:

We have an internal question about the Job alerts sent out to candidates. We have the 'Send Alert Every n Days' set to every 7 days.

My question is where / how does the system know what requisitions to pull into the list. Yes, I know it is based on the candidate preferences, but does the job have to be posted within those 7 days for it to show? Or what other criteria other than the job family/function is the alert based on? How old of requisitions will the alert pull if I just signed up for the talent community, only the last seven days since I have signed up?