Email / SMS

💼 Business Context

• Email/SMS engagement is a leading indicator of campaign ROI and channel fatigue
• Opt-out/consent events here are legally load-bearing — mishandling them creates compliance risk
• Owned by Lifecycle/CRM Marketing; consent state is shared with Legal/Compliance

🔌 Technical Overview

SendGrid and Twilio call a .NET Core Azure Function webhook endpoint for every engagement event (send, open, click, bounce, opt-out); the function validates the provider signature and forwards the event through Cxos.Ingestion.Client into the Ingestion API. The Stream Worker routes two priority tiers onto separate Azure Event Hubs consumer groups: standard engagement (opens/clicks) and compliance-critical (unsubscribes/bounces), so opt-outs are never queued behind bulk analytics traffic. The Analytics API (ASP.NET Core + Dapper) reads rollups from Azure Database for PostgreSQL Flexible Server for campaign dashboards.

💾 Sample Event Payload

{
  "event": "email_clicked",
  "event_id": "1e438f2b-3a9c-4c2d-8b1a-6f2e0d4a7c93",
  "timestamp": "2026-08-01T08:15:47Z",
  "user_id": "cust_004821",
  "context": {
    "channel": "email",
    "campaign_id": "camp_2291",
    "provider": "sendgrid"
  },
  "properties": {
    "link_url": "/summer-sale",
    "message_id": "msg_774f"
  }
}

🔗 Integration Points

• Azure Function webhook receivers for SendGrid / Twilio / Braze
• Cxos.Ingestion.Client NuGet package — shared contract for the outbound call into the Ingestion API
• Azure Event Hubs — dual consumer groups (standard vs. compliance-priority)
• Reverse ETL (.NET Core Activation API + Azure Functions) — suppression list sync back to the ESP

🧰 Services Consumed

• Owning microservice — Cxos.Ingestion.Api (see the Full Application Service Map)
• Database — Azure Cache for Redis (cache only, no system-of-record database)

⚠️ Non-Functional Considerations

• Scale: campaign sends can generate millions of webhook callbacks in a short burst — Azure Functions consumption plan scales out automatically
• Latency: opt-out events are applied within minutes via the compliance-priority Event Hubs consumer group
• Reliability: webhook handling is idempotent (event_id dedup) since providers frequently retry deliveries
• Security/Privacy: consent state is written to an auditable table in Azure Database for PostgreSQL, not just a marketing flag

🎯 Enterprise Example

A retail brand's promotional SMS blast generates an unsubscribe spike within 5 minutes. Because the Azure Function webhook receiver routes opt-out events onto the compliance-priority Event Hubs consumer group, every affected contact is suppressed from the next wave of the same campaign before it sends — avoiding a compliance incident and an estimated $40K in regulatory exposure.