← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary DKIM: From Theory to Production Implementation DKIM is a cryptographic email authentication standard that signs messages with the sender Architecture Scope Fleet Scale High-Volume Infrastructure Production Status 100% Inboxing Verified deliverability standard […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary List Quality and Infrastructure Performance: The Direct Connection Infrastructure cannot compensate for poor list quality. Bounce rate, complaint rate, and engagement rate — all driven by list quality — are the… Architecture […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary SPF Alignment Failure Modes: Why SPF Pass Does Not Mean DMARC Pass SPF authentication can pass while DMARC alignment fails. This note explains the distinction, the specific configurations that produce alignment failures… […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary IP Pool Architecture for High-Volume B2C Email Operations IP pool design for B2C email at scale: traffic category boundaries, IP count per pool, warming lead times, seasonal scaling, and per-pool monitoring. Architecture […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary Delivery Rate vs Inbox Placement Rate: Why the Difference Matters A 99% delivery rate tells you ISPs are accepting your messages — not where they put them. Inbox placement rate is the […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary What Operators Get Wrong About SMTP Connection Reuse SMTP connection reuse (pipelining multiple messages per session) is one of the most mis-configured aspects of email infrastructure. 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 Why Reputation Recovery Takes Longer Than Damage Email reputation can be damaged in hours by a single poor-quality campaign. Recovering from that damage takes weeks. 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 Operational Monitoring: A Starting Framework for Email Infrastructure Email infrastructure monitoring is often either absent or overcomplicated. Architecture Scope Fleet Scale High-Volume Infrastructure Production Status 100% Inboxing Verified deliverability standard MTA Engine […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary Technical Requirements for High Inbox Placement at Gmail Gmail inbox placement above 90% requires a specific set of technical configurations to be correctly implemented and maintained. 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 Economics of Email Infrastructure: Build vs Buy vs Managed Self-building, buying a managed service, or using a shared ESP — each email infrastructure model has a cost structure, operational burden, and… […]