For a non-technical marketing user to manage a campaign sending renewal reminders:

Data Filter: Use Data Filters to segment customers based on the expiration date included in the data file. This enables targeting customers 15 days and 7 days before subscription expiration.

Template-based Emails: Implement template-based emails to allow the marketing user to easily update and manage email content without needing technical skills or administrative rights.

Automation Studio: Utilize Automation Studio to schedule and automate the sending of these emails based on the specified criteria, streamlining campaign management.