Politejunction
Practical engineering writing for people who keep systems alive.
Email Deliverability: Authentication Beyond SPF
August 20, 2026
Relying strictly on SPF validation is long obsolete. Outbound mail can easily pass envelope checks while failing domain alignment, prompting modern receiving systems to evaluate cryptographic DKIM signatures and strict DMARC enforcement instead.
Cryptographic validation via DKIM carries the heavy operational load since signatures endure intermediary mail forwarding without relying on hop-by-hop IP reputation. Layering DMARC on top aligns the user-facing header address with validated identities, while its aggregated forensic feedback provides unmatched visibility into corporate mail streams.
When to Choose a Queue Over a Request
June 16, 2026
Traditional RPC calls remain popular due to straightforward causality: the client makes an invocation, waits for the response, and monitors latency directly. Asynchronous message queuing becomes essential when background tasks outlast active connections or when sudden volume surges threaten to overw…
A Practical Guide to API Rate Limiting
June 12, 2026
Few infrastructure components are treated with as much casual oversight as traffic throttling. Simple IP-based token buckets fall apart the moment traffic traverses cellular NAT gateways, causing thousands of legitimate handsets to suffer collective penalties for a single neighbor's surge.…
Zero-Downtime Deployments Without the Drama
June 19, 2026
Narratives surrounding uninterrupted deployments obsess over flashy infrastructure switching and instant green-blue cutovers. Real-world stability relies on mundane mechanics: deep readiness endpoints that confirm functional dependencies, complete socket draining, and backward-compatible persistence…
The Hidden Cost of Chatty Microservices
August 25, 2026
Refactoring centralized code into independent microservices trades code complexity for network unpredictability. Workflows that previously triggered simple internal methods suddenly require coordinated remote requests, each introducing separate latency budgets, retry loops, and partition hazards.…
More reading
- Why Edge Caching Still Matters in 2026 — Infrastructure, July 11, 2026
- Cache Invalidation Patterns That Survive Traffic — Data, April 24, 2026
- Practical Notes on Postgres Connection Pooling — Data, June 26, 2026
About us
Our contributors have spent years on-call for large platforms. This site collects the playbooks, postmortems and reference material we wish someone had handed us earlier.