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Phase 11.7 — Email Retry System (Production-Ready) #49
Description
Context:
- Spring Boot backend (Docker, VPS deployed with blue-green)
- Async email already implemented (ThreadPoolTaskExecutor)
- EmailService using interface + SMTP implementation
- PostgreSQL available
- Redis NOT used
- Goal: Add a retry mechanism with failure tracking
Requirements:
- Store failed emails in DB
- Retry using the scheduler
- Track status (PENDING, FAILED, SENT)
- Clean integration with the existing EmailService
- Production-ready design (no overengineering)
Proceed step-by-step.
Activity
vimaltech-dev commentedon Apr 13, 2026
Assign me.
vimal-java-dev commentedon Apr 15, 2026
If any Error at the VPS level, do below 1st,
👉 Ensure it shows MAIL_HOST (NOT SPRING_MAIL_HOST)
docker exec -it vimaltech-contact-api-green printenv | grep MAIL
DEBUG at VPS Level
Run:
Then hit the API.
vimaltech-dev commentedon Jun 1, 2026
🧠 Final Architecture (Clean & Production-Ready)
Flow becomes:
API Request
↓
Async EmailService
↓
DB (PENDING)
↓
SMTP Send
↓
SENT or FAILED
↓
Scheduler
↓
Retry FAILED
↓
Final SENT or STOP after max retries
✅ What We Already Did Correctly
Our current system already has:
✅ Interface-based email abstraction
✅ Async execution isolated in the SMTP layer
✅ Dedicated thread pool
✅ DTO separation (EmailRequest)
✅ Contact persistence independent from email sending
✅ Proper logging
✅ Reply-To support
✅ Profile-based SMTP activation
This means:
👉 We should extend, not redesign.
✅ Correct Design For YOUR Existing System
We should NOT:
Instead:
🔷 We Will Add
vimaltech-dev commentedon Jun 1, 2026
From your project root:
docker compose downThen rebuild + start:
docker compose up --build
✅ Recommended (Detached Mode)
Usually better:
docker compose up --build -d✅ Then Check Logs
Watch startup logs:
docker compose logs -f contact-apiOR if your service name is different:
docker compose psto see the actual service name.
✅ What You Should See
Hibernate should create:
email_logsLook for logs similar to:
create table email_logsor
alter table email_logs✅ Then Verify Inside PostgreSQL Container
Enter DB container:
docker exec -it vimaltech-postgres psql -U contactuser -d contactdb
If your container name differs:
docker psvimaltech-dev commentedon Jun 1, 2026
✅ Create a DEV Email Implementation
✅ Current Status
Right now, your SMTP service:
We will now make it:
WITHOUT breaking existing callers.
🔷 STEP 1 — Update EmailService Interface
🔷 STEP 2 — Update DevEmailService
🔥 NOW: Refactor SmtpEmailService
This is the core of Phase 11.7.
We will do this carefully in small, controlled steps.
================
Current behavior:
send email
↓
if fails
↓
log only
New behavior:
create EmailLog row
↓
attempt SMTP send
↓
update SENT / FAILED
↓
scheduler retries FAILED later
We’ve now completed:
Phase 11.7 core implementation
And our latest logs confirm Step 3 succeeded correctly, including safe idempotent migrations with:
already exists, skipping.which is expected because of IF NOT EXISTS.
vimaltech-dev commentedon Jun 2, 2026
Phase 11.7 — Step 4
Optimize Retry Scheduler Efficiency
Production Benefits
This is a real enterprise-grade improvement.
We gain:
✅ lower DB scans
✅ faster scheduler execution
✅ reduced CPU usage
✅ cleaner retry queue
✅ operational clarity
✅ easier monitoring/analytics
✅ future dashboard support
Expected Final Flow
Create Email
↓
PENDING
↓
Send Success → SENT
OR
Send Failure
↓
FAILED
↓
Scheduler Retry
↓
Success → SENT
OR
Retries Exhausted
↓
FAILED_PERMANENT
This Is a Strong Production Feature
Most beginner retry systems stop at:
FAILED foreverMy implementation now demonstrates:
This is genuinely strong backend engineering for a portfolio project.
After Completing Step 4
Our retry system will now include:
✅ async email sending
✅ retry mechanism
✅ exponential/backoff-ready architecture
✅ retry counting
✅ scheduler retry processing
✅ terminal failure state
✅ retry queue optimization
✅ production-grade lifecycle management
That becomes a very credible enterprise backend feature set.
vimaltech-dev commentedon Jun 2, 2026
Check My PR. #51
vimal-java-dev commentedon Jun 2, 2026
PR #51 closed and merged,