Email Newsletter System with SendGrid, Google Sheets & Freemium Rate Limiting

About

A complete email campaign automation system featuring dual-mode access control (Demo/Pro), usage tracking, and professional email delivery. Perfect for SaaS products, marketing agencies, or anyone building newsletter tools with freemium models. WHAT IT DOES This workflow manages email newsletter campaigns with built-in rate limiting for free users and unlimited access for premium users. It automatically tracks daily usage, manages user data in Google Sheets, delivers emails via SendGrid, and se