Phase 11.6: Async Email Integration with Thread Pool & SMTP Optimization

[vimal-tech-starter]

Summary

Implemented asynchronous email processing for the contact service to improve performance and scalability.

Changes

• Added @EnableAsync for async processing
• Implemented custom ThreadPoolTaskExecutor (emailExecutor)
• Converted email sending to non-blocking using @async
• Added SMTP timeout configuration to prevent thread blocking
• Improved logging for async email tracking

Result

• API response is now non-blocking
• Emails are processed in parallel threads
• Reduced latency from ~16s to ~3s
• Improved system scalability and resilience

Next Step

• Phase 11.7: Email retry mechanism with failure tracking

[vimal-tech-starter]

✅ Clean Fix (Minimal + Correct)

We will:

• Make SmtpEmailService conditional
• Provide a fallback (NoOpEmailService)
• Keep your ContactService unchanged (best design)

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• ✅ STEP 1 — Update SmtpEmailService
• ✅ STEP 2 — Add Fallback (CRITICAL)
• ✅ STEP 3 — No Change Needed in ContactService

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✅ FINAL ARCHITECTURE

• In Production (VPS)
• .env present
• spring.mail.host present

✅ SmtpEmailService used

• Emails sent

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In CI / Tests

• No .env
• No mail config
• ❌ SmtpEmailService NOT created
• ✅ NoOpEmailService used
• No crash

[vimal-java-dev]

🚀 RESULT

• PR already turned in ✅
• VPS still works ✅
• No hacks, no env tricks ✅
• Production-grade design ✅