SMTP Pool
Pool Architecture
How our managed SMTP pool works behind the scenes to deliver your emails reliably.
How It Works
SMTP Pool Architecture
┌─────────────────────────────────────────────────────┐
│ Your Instance │
│ │
│ Campaign → Queue → Worker → SMTP Selector │
│ │ │
└────────────────────────────────────┼─────────────────┘
│
┌────────────────┴────────────────┐
│ Pool Manager │
│ │
│ • Health scoring │
│ • Load balancing │
│ • Rate limiting │
│ • Rotation logic │
└────────────────┬────────────────┘
│
┌────────────────────────────┼────────────────────────────┐
│ │ │
┌────┴────┐ ┌────┴────┐ ┌────┴────┐
│ SMTP 1 │ │ SMTP 2 │ │ SMTP N │
│ Score:95│ │ Score:92│ │ Score:88│
└─────────┘ └─────────┘ └─────────┘Pool Components
- SMTP Selector: Chooses optimal SMTP based on health score, load, and your plan tier
- Health Monitor: Continuous monitoring of delivery rates, bounce rates, and response times
- Rate Limiter: Enforces per-SMTP and per-customer sending limits
- Rotation Engine: Automatically rotates between SMTPs to distribute load
Health Scoring
Each SMTP maintains a health score (0-100) based on:
| Factor | Weight |
|---|---|
| Delivery Rate | 40% |
| Bounce Rate | 30% |
| Response Time | 15% |
| Uptime | 15% |
SMTPs with scores below 70 are automatically removed from the active pool until issues are resolved.