A customer wants a list of subscribers who were sent an email within the past...

To get a list of subscribers who were sent an email within the past 12 months, you should query the Job and Sent data views. These data views contain detailed information about email sends and can be used to filter subscribers based on the send date.

SQL Query Example:

SELECT s.SubscriberKey FROM _Sent s JOIN _Job j ON s.JobID = j.JobID WHERE j.SendDate >= DATEADD(month, -12, GETDATE())

Salesforce Data Views