Set Email Subscription Notifications to remind on custom set schedules

[StevenLooney]

There is a notification that gets sent out automatically when an Email Subscription to a report is about to expire. The suggestion here is to have an option to customize when this email goes out and how often this will get sent. For example, if the subscription is ending in 30 days, the ask would to be able to set up notification emails that go out 15 days before the subscription ends. Basically, just able to customize the time and frequency of these notifications. This will help control the subscription process more thoroughly.