The Annual Deliverability Audit: A January Checklist
January is the quiet window between peak seasons. The full-stack audit that catches drift in authentication, DNS, list hygiene, and monitoring before it costs mail.
#Authentication
9 articles with this tag
2025 in Email: The Year Authentication Became Mandatory Everywhere
Microsoft joined the mandate, Gmail moved to hard rejection, and DMARCbis reached the finish line. What 2025 changed for senders and what it sets up for 2026.
SPF's 10-Lookup Limit: Includes, Flattening, and Permerror
Every include, a, mx, and redirect in your SPF record costs a DNS lookup, and the budget is ten. Why records break at scale and how to fix them without flattening regret.
DKIM Replay Attacks: How Spammers Weaponize Your Valid Signatures
A DKIM signature stays valid no matter who forwards the message. How replay attacks abuse that property to spend your reputation, and the defenses that limit the damage.
Why DMARC Alignment Matters More Than DMARC Itself
DMARC fails when SPF or DKIM pass for the wrong domain. The alignment rules, relaxed vs strict modes, and the ESP configuration that fixes it.
Yahoo and Gmail's February 2024 Bulk Sender Requirements: A Compliance Checklist
The complete compliance checklist for Yahoo and Gmail's February 2024 bulk sender requirements. Authentication, unsubscribe, complaint rates—what you actually need.
The ARC Header: How Forwarding Breaks DMARC and What You Can Do
Forwarders break DMARC by modifying messages in transit. ARC (RFC 8617) preserves authentication results across hops. How it works, who supports it, and the limits.
Understanding DMARC Policies: From p=none to p=reject Without Breaking Things
How to move from DMARC p=none to p=reject without breaking production mail. The phased rollout that actually works with the failures most senders hit.
DKIM Explained: How a Signature Proves the Mail Is Yours
SPF authorises servers, DKIM authenticates messages. How the signing and verification cycle works, what each tag in the header does, and where signatures break.