Mailgun Push

Transactional notification pipelines have a habit of silently failing in production, messages that show as 'sent' in your dashboard but never arrive in an inbox. The failure modes are well-documented: ISP filtering, webhook delivery gaps, retry storms, and the quiet drop that happens when a bounce isn't handled correctly. This project builds a reliable transactional messaging service on top of Mailgun, engineered specifically to handle the edge cases that cause pipelines to fail silently.

1. 1.
   Reliable Email Delivery: Integrate Mailgun with retry logic, bounce handling, and delivery status tracking, so failures are visible before users report them.
2. 2.
   Push Notification Delivery: Extend the pipeline to push notifications across mobile and web channels, with the same delivery reliability standards as email.
3. 3.
   Observability: Build delivery observability into the system from the start, not as an afterthought, so delivery failures appear in dashboards rather than support tickets.
4. 4.
   Failure Recovery: Implement failure detection and automatic retry with exponential backoff, handling the transient failures that cause permanent drop in naive implementations.

• ◆
  Failure Mode Catalogue: Documented the 12 most common transactional email failure modes from production incidents and Mailgun's own documentation before writing any integration code.
• ◆
  Webhook Handler Design: Built robust webhook handlers for Mailgun's delivery events, delivered, bounced, complained, dropped, with idempotency keys to prevent double-processing.
• ◆
  Retry Architecture: Implemented exponential backoff with jitter for transient failures, with dead-letter queue handling for messages that exceed the retry budget.
• ◆
  Delivery Dashboard: Built a lightweight delivery status dashboard showing per-message delivery state, bounce rates by domain, and alert thresholds for anomalous failure rates.

A notification system that crashes visibly is easy to fix, you see the error, you fix the error. A notification system that silently drops 3% of messages is much harder to detect and much more damaging, because it erodes user trust gradually and invisibly. The observability design in this project treats 'delivered' as a claimed state that requires positive confirmation from the receiving mail server, not just 'we called the API and got a 200'. Every message is tracked through its full lifecycle until confirmed receipt or terminal failure.

Silent notification failures are invisible to most product metrics until a user complains. I designed observability into this from the start, not as an afterthought.

Reliable multi-channel message delivery with visibility into failures before users report them.