The Context

After tuition settlement, we identified 1,900+ students who paid more than they should have.
Parents needed to securely submit their bank details for refunds.

However, announcing this refund process to thousands of parents at once meant:

• Massive concurrent access the moment emails were sent
• Risk of server overload
• Need for a hard deadline (a refund window that must close automatically)

We needed a system that was fast, secure, and impossible to overwhelm.

The Challenge

1. High Traffic Burst
   Parents typically open the email within seconds. Traditional servers—especially our cPanel environment—would not scale.
2. Refund Window Control (Kill-Switch)
   Once the deadline passed, the portal had to instantly close without manual intervention.
3. Bulk Email Deliverability
   Sending 1,900+ refund emails in one blast risks IP throttling or spam issues.
4. Full-Stack Delivery on Mixed Infrastructure
   • Frontend must be highly available (AWS)
   • API must run on cPanel (due to existing banking IP whitelisting)
   • Everything must integrate smoothly

The Solution

I built a hybrid Serverless + Edge-Controlled architecture that decoupled frontend load from backend constraints.

1. Automated Refund Eligibility Extraction

I pulled overpayment data directly from our payment gateway, processed the dataset, and generated a clean list of eligible students.

2. High-Deliverability Email Blast

I wrote a Python script with:

• SMTP rotation across multiple gateways
• Rate control to avoid throttling
• Error logging + retry queue

Parents received a unique, secure link to the refund portal, with a 99%+ inbox rate.

3. Zero-Server Frontend (AWS S3 + CloudFront)

The entire refund portal UI was:

• Deployed to S3 (static hosting)
• Distributed via CloudFront for global caching
• Able to handle thousands of concurrent visitors
• Costing less than $5 USD in total

4. Refund Window "Kill-Switch" Using CloudFront Function

Instead of checking backend availability or hitting the database, I implemented logic at the edge:

• A CloudFront Function runs on every request
• It checks the current timestamp
• If the refund period has ended → instantly redirect to “Closed” page
• No backend call is ever made for expired access

Impact:
Zero load on cPanel, instant shutdown, tamper-proof logic, globally fast.

5. API Hosted on Existing cPanel

Due to BCA whitelisting constraints, the API remained on the existing infrastructure:

• PHP backend for form submission
• Database logging
• Validation + duplicate submission prevention

CloudFront simply passed allowed traffic through during the active refund window.

The Result

The system successfully processed refunds for 1,900+ parents within the required window.

• 100% uptime, even during peak traffic
• Zero overload on cPanel thanks to edge filtering
• Highly secure access with instant “kill switch”
• Refund portal built, deployed, and delivered in record time
• AWS cost remained under $5 USD for the entire period

This architecture demonstrated how serverless design and edge computing can solve high-traffic operational challenges without heavy infrastructure.