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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

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Technical notes

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

Built for operators

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

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Browse by issue, provider, workflow, or stack area when you need a fast starting point for investigation.

Linux operator following a protected Bash execution path through quoting, expansion, conditions, functions, pipelines, parallel jobs, cleanup, and verified results

Linux, MTA & Security · Nov 14, 2022 · 2 min read

Bash Features

The table lists shell features that can help you choose between sh, csh, ksh, Bash, tcsh, Zsh, rc, and es.

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.

Java source and project configuration move through dependency resolution, compile, test, package, verify, install, and controlled artifact publication with quality gates and repositories

DevOps & Cloud · Oct 22, 2022 · 21 min read

Apache Maven for Java: Installation, Builds, Dependencies, CI, and Troubleshooting

Learn Apache Maven from installation and a first Java project through lifecycle phases, dependencies, multi-module builds, repository security, CI, releases, and troubleshooting.

A private key remains protected while its certificate request travels to a certificate authority and the signed certificate returns to a TLS server

Linux, MTA & Security · Oct 2, 2022 · 16 min read

Create a CSR Using OpenSSL: Keys, SANs, Verification, and Deployment

Generate and verify an OpenSSL certificate signing request, protect its private key, include SANs, validate the issued certificate, and deploy it safely.

A shell script moves through controlled build and distribution stages while runtime logic remains observable and secrets arrive through a separate protected path

Linux, MTA & Security · Sep 29, 2022 · 18 min read

Protecting Shell Scripts: shc, Encryption, Signing, and Runtime Secrets

Use shc, GnuPG, signatures, permissions, and runtime secret delivery honestly, with clear limits, repeatable builds, validation, and rollback.

Linux, MTA & Security · Sep 29, 2022 · 16 min read

Configure Your Own Squid Proxy Server: Secure Step-by-Step Guide

Install and secure an explicit Squid forward proxy with source ACLs, user authentication, safe ports, firewall rules, client configuration, logging, troubleshooting, and rollback.

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.

Labelled Apple Mail BIMI flow showing authenticated sender, DMARC enforcement, evidence document, receiving provider checks and supported Apple clients

Email Deliverability · Sep 25, 2022 · 12 min read

Apple Mail Added BIMI in 2022: Verified Logos Across Apple Clients

A practical guide to Apple Mail’s 2022 BIMI support, including release timing, authentication, logo evidence, provider dependencies and validation.

Platform engineer operating a secure container workflow with isolated applications, image delivery, private networking, persistent storage, and observability

Linux, MTA & Security · Sep 1, 2022 · 21 min read

Docker Container

Learn what every Docker command and option does, then install Docker, run containers, use images, volumes, Dockerfiles, Compose, and add a node.