Field notes on Email Authentication.
Every OSH post tagged Email Authentication: practical write-ups from real engagements, not vendor decks.
Everything filed under Email Authentication
Posts from OSH engineers working in Email Authentication. Migrations that went sideways, configurations we have learned the hard way, and the practical decisions worth writing down.
Cyber Insurance and DMARC: What Underwriters Actually Want to See
Cyber-insurance underwriters now read your DMARC policy tag, MFA scope, and EDR roster. Here is what a 2026 renewal questionnaire asks and …
Read field noteDMARC: Why Your Small Business Email Is a Literal Open Window for Arsonists
Small business email without DMARC is a wide-open window any arsonist can climb through. Here's what the spoof looks like to your customer …
Read field noteHow to Check If Your Suppliers and Clients Are DMARC Compliant
Your suppliers' weak DMARC posture turns into your fraud problem. Here is how to check any supplier or client domain in 30 seconds and what …
Read field noteReading Microsoft 365 and Google Workspace Email Headers Like a Pro
Read M365 and Google Workspace email headers without flinching. Six lines triage 90% of mail-flow questions, with worked phishing and …
Read field noteThe Bouncer's Guide to DMARC: Securing Your Email Domain
DMARC is the bouncer for your email domain. A practical guide to SPF, DKIM, DMARC alignment, and the policy escalation from p=none to …
Read field noteThe Small Business DMARC Bridge: From p=none to p=reject in Four Weeks
A pragmatic 4-week sprint plan for small businesses to take DMARC from p=none to p=reject. Real services, real timelines, real guardrails.
Read field noteWhat Does p=reject Actually Mean (And When Should You Set It)?
p=reject is the strongest DMARC policy. Plain-English guide to what it instructs receivers to do, when to set it, and how to ramp safely …
Read field noteYour employer signed you up for a game show. You didn't audition.
If your employer hasn't deployed DMARC, you're a contestant in a game show you never signed up for. What's at stake, and how to get yourself …
Read field noteGot a email authentication problem we haven't written about?
If you are stuck on something we have not covered, tell us. The next field note is usually a client question we did not have a tidy answer for yet.
