← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary Email Infrastructure and Regulatory Compliance in Europe Operational guide to email regulatory compliance for senders operating in Europe in 2026. Architecture Scope Fleet Scale High-Volume Infrastructure Production Status 100% Inboxing Verified deliverability […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary The Cost of Poor Bounce Handling: More Than Just List Quality Poor bounce handling costs more than list bloat — it damages IP reputation through repeated sends to invalid addresses, wastes throughput […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary Deliverability Requires Infrastructure Expertise: Why Strategy Alone Is Not Enough Email deliverability strategy without infrastructure execution produces poor results. 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 PowerMTA vs Postfix at Production Volume: An Operational Comparison Postfix handles email delivery for millions of servers. PowerMTA is purpose-built for high-volume commercial sending. 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 Header Analysis: What Receiving Servers Evaluate Receiving servers evaluate specific headers in every message before delivering or filtering it. Architecture Scope Fleet Scale High-Volume Infrastructure Production Status 100% Inboxing Verified deliverability […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary Building a Multi-Brand Email Sending Architecture: Isolation Patterns That Actually Work in 2026 Architectural guidance for organisations sending email for multiple brands, agencies managing multi-client portfolios, and SaaS platforms providing email… Architecture […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary The Volume Thresholds That Trigger ISP Filtering ISPs apply enhanced scrutiny at specific volume thresholds. Architecture Scope Fleet Scale High-Volume Infrastructure Production Status 100% Inboxing Verified deliverability standard MTA Engine PowerMTA & […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary SPF Record Complexity and Delivery Failure Risk SPF records become delivery liabilities when they exceed 10 DNS lookups. Architecture Scope Fleet Scale High-Volume Infrastructure Production Status 100% Inboxing Verified deliverability standard MTA […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary Lessons from Building Infrastructure for European Senders What European senders deal with that US providers rarely account for: GMX and Web.de thresholds, OVH peering behaviour, GDPR data residency, and regional… Architecture Scope […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary Sender Identification and ISP Attribution: How ISPs Know Who You Are ISPs attribute email signals to senders through multiple identification mechanisms: From: address, DKIM signing domain, PTR record, IP address, and… Architecture […]