High-volume SaaS platforms require redundant SMTP clusters capable of surviving node failures without dropping transactional messages. Combining HAProxy with Postfix ensures high-availability delivery.
1. High-Availability SMTP Architecture Diagram
🌐 Redundant Cluster Flow
[Application Cluster]
│ (Round-Robin TCP)
▼
[HAProxy Node 1 / 2 (Keepalived VRRP VIP: 10.0.0.10:587)]
│
┌─────┴─────┐
▼ ▼
[Postfix 1] [Postfix 2] (Dedicated Outbound IP Pools & Shared Redis Rate Limiting)