Does Users Receiving Expiration Notifications For Older Contracts?

Summary:

We would like to know how Send Contract Expiration Notifications works?We kept this on hold for sometime for contract conversion from the legacy system and now we want to release the hold so that the expiry notification can be send.

Content (required):

We kept this program on hold for sometime for contract conversion from the legacy system and now we want to release the hold so that the expiry notification can be send. So we would like to know whether it sends notification to the older contracts which are expired and closed or only it would send it to the Active contracts. Can someone please respond asap on this?