← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary What ISP Postmaster Teams See When They Look at Your Domain ISP postmaster teams have access to data about your sending that most senders never see. 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 Mechanics of Domain Reputation at Gmail Gmail domain reputation is the primary inbox placement signal for high-volume senders. 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 Send-Time Distribution and ISP Acceptance Rate Optimisation When you send matters as much as what you send. This note documents how send-time distribution across a campaign window interacts with ISP rate limits… […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary Encoding Issues That Break DKIM Signatures in Production DKIM signatures break when message content is modified in transit. 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 Why Dedicated IPs Outperform Shared Pools at Volume At sufficient volume, dedicated IP addresses consistently deliver better inbox placement than shared pools. Architecture Scope Fleet Scale High-Volume Infrastructure Production Status 100% Inboxing […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary The Role of List Age in Deliverability Older lists generate more bounces, more complaints, and more spam trap hits than recently acquired lists. 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 Modern ISP Content Scoring Systems Work Content scoring has evolved from keyword blacklists to multi-signal ML systems that evaluate message structure, sender reputation, engagement history, and… Architecture Scope Fleet Scale High-Volume […]
← Back to Operational Notes Archive Engineering Operational Note · Published Production Engineering Memo · Technical Architecture · 14 min read Executive Summary Capacity Planning for Email Infrastructure: A Methodology Email infrastructure capacity planning requires matching IP count, server resources, and queue architecture to sending volume, accounting for peak… 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 Multi-Datacenter Email Infrastructure Failover When does multi-datacenter email infrastructure make commercial sense, and what does the architecture look like? 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 Why DMARC Reporting Is Underused — and What You're Missing DMARC aggregate reports contain the deepest sender identity intelligence available from ISPs. Most programmes that have DMARC deployed are not readin Architecture […]