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Practical field notes for teams diagnosing email deliverability, DNS authentication, sender reputation, Linux, MTA, cloud, monitoring, and DevOps failures.

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Technical knowledge system connecting email identity, secure mail flow, servers, cloud operations, monitoring, and runbooks

182 Published articles

10 Topic tracks

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Technical notes

Articles on email deliverability, DNS, Linux, MTA operations, DevOps, monitoring, and incident recovery.

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Short, practical guidance for teams that need to diagnose, repair, and run production email systems.

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Shared and dedicated email IP models are compared by volume, isolation, operational staffing, ramp capacity and cost before common authentication and monitoring controls

Email Infrastructure & Authentication · Feb 18, 2026 · 12 min read

Dedicated vs Shared IP for Email: Capacity and Reputation

A practical infrastructure decision framework that compares shared pools and dedicated IPs without treating either model as an automatic deliverability upgrade.

A sending MTA discovers an MTA-STS DNS record, retrieves and caches an HTTPS policy, validates MX STARTTLS certificates and either delivers or queues for retry

Email Infrastructure & Authentication · Feb 15, 2026 · 13 min read

MTA-STS: Enforce TLS for Inbound Email Delivery

A staged implementation guide for MTA-STS policy hosting, MX matching, certificate validation, testing, enforcement, monitoring and incident recovery.

A recipient domain publishes a TLS-RPT DNS policy while sending MTAs aggregate TLS successes and failures into JSON reports, parsing, alerts and remediation

Email Infrastructure & Authentication · Feb 14, 2026 · 13 min read

TLS-RPT for Email: Publish, Read and Act on Reports

An operations guide to publishing TLS-RPT, ingesting aggregate JSON safely and converting transport-security reports into actionable evidence.

An originating message is assessed with SPF, DKIM and DMARC before a forwarder adds ARC authentication results, a message signature and a seal for final receiver validation

Email Infrastructure & Authentication · Feb 12, 2026 · 14 min read

Authenticated Received Chain (ARC): Forwarding and Mailing Lists

How ARC preserves authenticated handling evidence across forwarders and mailing lists, what receivers can infer from it and how to troubleshoot a broken chain.

An outbound email passes through three authentication checkpoints before a mailbox gateway accepts or rejects the message

Email Infrastructure & Authentication · May 1, 2025 · 15 min read

Microsoft Outlook High-Volume Sender Requirements: Enforcement Guide

Meet Microsoft Outlook.com high-volume sender requirements, validate SPF, DKIM and DMARC, diagnose 550 5.7.515, and monitor every customer domain.

One email message receives an opaque identity token that remains connected as the message crosses several mail servers on its delivery path

Email Infrastructure & Authentication · Feb 21, 2025 · 25 min read

Email Message-ID Implementation: A Production Guide

Implement globally unique Message-ID headers, trace customer abuse safely, protect recipient privacy, preserve retry identity, and correlate delivery events.

Email Infrastructure & Authentication · Feb 2, 2025 · 15 min read

Implementing BIMI for Brand Recognition: A Production Guide

Implement BIMI step by step with enforced DMARC, a valid SVG Tiny-PS logo, VMC or CMC selection, certificate application, DNS, hosting, and provider testing.

A modular email operations control plane connects customer data, content, and application events to managed delivery, marketing automation, and self-managed MTA paths

Email Infrastructure & Authentication · Nov 7, 2022 · 18 min read

ESP and Email Tools: Choosing a Production Stack

Choose an ESP, delivery API, marketing platform, MTA, testing system, and provider diagnostics from evidence, traffic requirements, and exit controls.

Security administrator monitoring connected governance, servers, cloud services, identities, endpoints, and protected recovery systems

Email Infrastructure & Authentication · Sep 29, 2022 · 29 min read

Security Administrator Guide: Skills, Tasks and Interview Questions

A practical security administrator guide covering baselines, identity, hardening, logging, incident response, recovery, commands, scenarios, and 200 preparation questions.