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Everything on this site, organized by topic. Each article is written for people who understand email but haven't spent years inside mail server infrastructure.

Whiteboard diagram showing SPF record structure with authorized sender IP addresses mapped to a domain, photographed in a sunlit academic workspace
Authentication

SPF Records: What They Actually Contain and How to Read Them

SPF records are plain text, but the syntax isn't obvious. This walkthrough shows you how to read any SPF record, what each mechanism means, and how to tell whether your record covers all your sending sources.

9 min read Beginner
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Close-up of a laptop screen showing DKIM email header with cryptographic signature text, shallow focus, warm ambient library light, academic setting
Authentication

DKIM Signatures: How the Cryptography Works Without the Math

DKIM uses public-key cryptography, which sounds intimidating. This article explains the concept using a physical analogy that makes the mechanism clear, then connects it back to what you see in email headers.

11 min read Beginner
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Hand-drawn flowchart on graph paper showing DMARC policy decision tree with pass and fail branches, photographed on a wooden desk with pencil resting beside it
Authentication

DMARC Policy: From Monitoring to Enforcement Without Breaking Your Email

Moving from p=none to p=reject is the goal, but doing it without first reading your aggregate reports can silence legitimate sending sources. This guide walks through the transition step by step.

14 min read Intermediate
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Abstract visualization of email filtering layers shown as translucent screens with data flowing through, cool blue tones in a dark scholarly workspace
Reputation

Spam Complaint Rates: What Counts, What Doesn't, and What Thresholds Matter

Not every spam complaint is created equal. Gmail's FBL, Apple's complaint data, and Yahoo's thresholds each work differently. Understanding what counts as a complaint in each system changes how you interpret your numbers.

10 min read Intermediate
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Overhead shot of a notebook with hand-drawn reputation scoring diagram, pen resting beside it, warm desk lamp illuminating the page in a quiet study room
Reputation

Why Buying an Email List Creates Reputation Damage That Outlasts the Campaign

The damage from purchased lists isn't just about the emails that bounced or the complaints that came in. The mechanisms that make the damage lasting are more subtle and more important to understand.

12 min read Beginner
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Laptop screen showing Gmail inbox with tabbed interface in focus, shallow depth of field, person's hands visible on keyboard, bookshelf background slightly blurred
Gmail

Gmail's Promotions Tab: The Signals That Decide Where Your Newsletter Goes

The Promotions tab isn't necessarily bad for your newsletter. But understanding what puts email there, and what doesn't, gives you more control over where your messages land and what your subscribers experience.

13 min read Intermediate
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iPhone and MacBook side by side on a library desk, Apple Mail app visible on both screens, soft warm ambient light, scholarly setting with books visible in background
Metrics

Open Rates After Apple MPP: What Your Dashboard Numbers Now Mean

Apple's Mail Privacy Protection has made open rate reporting genuinely unreliable as a measure of human engagement. This article explains the mechanism, the scale of the effect, and which metrics to watch instead.

8 min read Beginner
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Person at a wooden desk using a laptop with spreadsheet visible, organizing contact list data, library shelves in background, focused expression, warm overhead lighting
List Management

Re-Engaging a Cold List: A Staged Approach That Protects Your Sender Reputation

Sending to a list that's been quiet for six months or more requires a different approach than your regular sending cadence. The risk profile is different, the re-engagement sequence needs to reflect that, and the signals to watch are different too.

15 min read Intermediate
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