Paul O'Brien DMARC Explained: What Happens When Email Auth Fails DMARC passes only when SPF or DKIM passes and aligns with your From domain. Here is what a DMARC fail means and how to fix it. Email Authentication8 min read 
Paul O'Brien SPF Explained: What It Proves and Why It Fails SPF lists which servers may send email for your domain, but it checks the delivery path, not the sender people see. This guide covers record syntax, ~all vs -all, the 10-lookup limit and why legitimate mail fails. Email Authentication8 min read 
Paul O'Brien SPF, DKIM & DMARC: How Email Authentication Works Email was built on trust, so the From line can be faked. This guide explains how SPF, DKIM and DMARC work together, adds MX, MTA-STS and BIMI, and points to the detailed guide for each. Email Authentication6 min read 
Paul O'Brien Can You Get Disciplined for an Email Mistake? Email mistakes at work are common, but when do they lead to discipline? Here’s how UK employers weigh intent, risk and impact, what a fair process looks like, and what to do in the first hour after you hit send. Email6 min read 
Paul O'Brien Zero-Access Encryption: What It Really Means (2026 Guide) Zero-access encryption stops your provider reading stored mail, but not metadata or inbound mail before it arrives. Here is what it covers, how it differs from end-to-end, and the trade-offs. Email Privacy10 min read 
Paul O'Brien Why Use Your Own Email Domain? Cost, Setup and Risks An address on your own domain stays yours when you change provider. This guide covers what it costs, which providers support custom domains, how to move without losing mail and how to protect the domain. Email Privacy7 min read 
Paul O'Brien DKIM Explained: What It Proves and Why It Fails DKIM signs your email so receivers can check it wasn't altered, but it proves integrity, not identity. This guide covers signatures, selectors, key length, provider setup and why genuine mail fails. Email Authentication7 min read 
Paul O'Brien Why Marketing Emails Only Offer Unsubscribe Links Why so many marketing emails force a binary choice between staying and leaving, and how unsubscribe-only design misses what subscribers actually want. Email7 min read 
Paul O'Brien DuckDuckGo Email Protection Review: Free Tracker Removal DuckDuckGo Email Protection forwards mail through free @duck.com addresses and strips the trackers it recognises. Here is what it does, what it cannot do and when to choose something else. Email Privacy6 min read 
Paul O'Brien StartMail Review 2026: Features, Trade-offs, and Enterprise Security StartMail puts unlimited aliases, open IMAP/SMTP and IP header stripping at the heart of a paid-only, Dutch-based inbox. I look at pricing, PGP, the Business plan and where it falls short of Proton Mail and Tuta in 2026. Email Providers9 min read 
Paul O'Brien How to Set Up a YubiKey for Email: Gmail, Outlook, Proton and Fastmail A step by step guide to protecting your email with a YubiKey or other security key. How to add one to Gmail, Outlook, Proton (including Proton Pass) and Fastmail, when to use it as a passkey, and how to set up a spare so you never get locked out. Email Security13 min read 
Paul O'Brien The History of Email: From a 1971 Hack to the Web's Identity Layer Email began as a quick hack between two computers in the same room, and it still runs on rules written in 1982. Here's how it grew from ARPANET into the backbone of online identity, and what that history means for choosing a provider today. Email13 min read 