Case Study: Delivering A Million Unique Barcodes with MailChimp

By: Syed Raiyan

One of my clients needed a newsletter template in MailChimp that could send a unique barcode to each of their 1 million recipients. The challenge? The barcodes were already pre-generated, totaling around 12GB of images. My job was to ensure that every recipient got their correct barcode without any duplicates and that the emails worked perfectly on all devices and email clients.

Challenges

  • Huge Data Size: The 1 million barcode images added up to approximately 12GB. 
  • Avoiding Duplicate Assignments: Each recipient had to get a unique barcode. 
  • Seamless Email Display: The email template had to be compatible with 99% of email clients and devices. 
  • Efficient Hosting & Delivery: The large dataset needed a fast and reliable hosting solution.

Solution

  • Custom MailChimp Merge Tags – I created a custom merge tag system that dynamically pulled the correct barcode image for each recipient. 
  • AWS CloudFront for Hosting – I suggested using AWS CloudFront to store and distribute the barcode images efficiently. 
  • Code Optimization – I carefully structured the code to ensure that the same barcode was never assigned twice. 
  • Litmus Testing – I tested the email template across 90+ email clients and devices. 
  • MailChimp Tracking – MailChimp handled the tracking part, ensuring correct delivery.

Results

  • ✅ 1 Million Unique Barcodes Delivered – Each recipient received their correct barcode with zero duplication. 
  • ✅ 99% Compatibility Across Devices – The emails displayed perfectly on all major email clients and devices. 
  • ✅ Fast & Reliable Performance – AWS CloudFront ensured smooth and quick image delivery. 
  • ✅ Client Satisfaction – The client was extremely happy with the seamless execution and efficiency of the campaign.
  • ✅ MailChimp Tracking – MailChimp handled the tracking part, ensuring correct delivery.

Final Thoughts

This project was a great example of how the right combination of email marketing expertise, strategic coding, and cloud hosting can solve complex challenges. By optimizing every step of the process, I ensured that the campaign ran smoothly, making the experience effortless for both the client and their recipients.