Architecture & Bulk Delivery Engine:
- Goal: Send 50 million promotional and transactional emails in a 2-hour window while maintaining high sender reputation and avoiding ISP spam blocks.
1. Campaign Segmentation & Sharding:
- Customer audience lists store in an analytical datastore (ClickHouse or Snowflake).
- Pre-processing job executes segmentation filters and chunks recipients into batches of 1,000, publishing campaign tasks into Kafka.
2. Distributed Rendering & Personalization:
- Worker fleet pulls batches from Kafka, renders personalized content (name, customized discount codes), and formats MIME messages.
3. ISP-Aware Outbound Rate Limiting & Warmup:
- ISPs (Gmail, Yahoo, Outlook) enforce strict, dynamic receiving rate limits.
- Dedicated MTA (Mail Transfer Agent) cluster (e.g., Haraka or Postfix) partitions outbound queues by recipient domain.
- Intelligent IP Pool Routing: Route high-reputation senders over warm dedicated IPs; route new accounts over monitored shared pools.
4. Feedback Loops & Reputation Protection:
- Webhook ingestion pipeline processes automated bounces, unsubscribes, and spam complaints.
- Suppresses bounced or complaining emails instantly in the global suppression list to protect domain deliverability.