← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary Why Dedicated Infrastructure Scales Differently Than Shared ESPs Shared ESPs and dedicated sending infrastructure scale along different curves. At low volume, shared ESPs win on simplicity and cost. Architecture Scope Fleet Scale […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary Operational Protocols for Managing IP Reputation Events IP reputation events — blacklistings, SNDS status changes, Postmaster Tools IP reputation declines — require structured response protocols. Architecture Scope Fleet Scale High-Volume Infrastructure Production […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary List Hygiene Practices That Preempt Deliverability Problems Most deliverability problems are preventable through list hygiene practices applied before they become incidents. Architecture Scope Fleet Scale High-Volume Infrastructure Production Status 100% Inboxing Verified […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary Infrastructure Behind OTP Delivery: Engineering for Near-Zero Latency One-time password and two-factor authentication codes are the most latency-sensitive email messages a programme sends. Architecture Scope Fleet Scale High-Volume Infrastructure Production Status 100% […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary How Engagement Data Should Drive Sending Infrastructure Decisions Engagement data — opens, clicks, complaint rates, and unsubscribes — should determine more than campaign segmentation. Architecture Scope Fleet Scale High-Volume Infrastructure Production Status […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary SMTP Authentication Mechanisms Compared: SPF, DKIM, DMARC, and ARC SPF, DKIM, DMARC, and ARC each solve different authentication problems and interact in specific ways. Architecture Scope Fleet Scale High-Volume Infrastructure Production Status […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary Configuring Email Infrastructure for High-Frequency Transactional Sending Transactional email at high frequency — 2FA codes, password resets, real-time notifications — has different infrastructure requirements than… Architecture Scope Fleet Scale High-Volume Infrastructure Production […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary SMTP Rate Limiting Strategies and ISP Relationship Management ISP rate limits are not obstacles to work around — they are signals from ISP reputation systems about the current trust level they extend […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary DMARC Enforcement Migration: Lessons from Large-Scale Deployments Migrating from DMARC p=none to p=quarantine and p=reject requires a sequenced process that identifies all sending sources, verifies authentication… Architecture Scope Fleet Scale High-Volume Infrastructure […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary The Queue as a Diagnostic Tool: Reading MTA Queue State The PowerMTA queue is more than a delivery backlog — its structure, depth, and composition at any moment reveal the exact cause […]