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

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Created by: Gilbert Onyebuchi || gilbert-onyebuchi

Gilbert Onyebuchi

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Last update 8 hours ago

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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 sends real-time notifications through Telegram.

KEY FEATURES

  • Dual-Mode System: Demo mode (5 emails/day) and Pro mode (unlimited)
  • Smart Rate Limiting: Automatic daily counter reset
  • User Management: Automatic new user registration and tracking
  • Google Sheets Integration: Stores user data, send counts, and usage history
  • Professional Email Delivery: SendGrid integration for reliable sending
  • Real-Time Monitoring: Telegram notifications for every send
  • Ready-to-Use Templates: 4 professional email designs included (Modern, Professional, Promotional, Newsletter)
  • Live Preview: See exactly how emails look before sending
  • HTML Export: Copy email HTML for use in any platform

HOW IT WORKS

  1. User accesses the Email Newsletter Builder web form
  2. Designs email using one of 4 professional templates
  3. Chooses Demo or Pro mode
  4. Webhook receives the email data and configuration
  5. Workflow checks mode (Demo/Pro)
  6. For Demo mode:
    • Queries Google Sheets for user email
    • Checks if user exists and validates daily limit (<5 sends)
    • If new user: Creates database entry
    • If existing user + under limit: Increments counter
    • If limit reached: Returns error message
  7. For Pro mode: Sends immediately without limits
  8. SendGrid delivers the email
  9. Google Sheets updates with new send count and timestamp
  10. Telegram notification sent to admin
  11. Success/error response returned to user

SETUP REQUIREMENTS

  1. Google Sheets account (free)
  2. SendGrid account (free tier: 100 emails/day)
  3. Telegram account + bot (free)
  4. n8n instance (self-hosted or cloud)

SUPPORT & FEEDBACK
Questions or issues? Connect with me on LinkedIn
Want to see it in action? Try the live demo: Click here

⭐ If you find this workflow helpful, please give it a rating and share your feedback!