Articles & Guides
Useful resources for web developers and system administrators
Security
BIMI Setup Guide: Brand Logo in Email
BIMI shows your brand logo next to email. How to set it up: SVG Tiny PS logo, a VMC certificate, the default._bimi TXT record and required DMARC enforcement.
Security
Migrating DMARC to p=reject Safely
Migrate DMARC from p=none to quarantine and reject without losing legitimate email: a staged pct rollout, reading RUA reports, and monitoring with enterno.io.
Security
Reading DMARC Aggregate (RUA) Reports
Reading DMARC RUA reports: how to parse XML aggregates, source IP, SPF and DKIM results, alignment and disposition. Move from p=none to p=reject safely.
Security
Email Spoofing Prevention
Email spoofing prevention: how spoofing works and how to stop it with SPF, DKIM and DMARC together. Real records, dig verification and the p=reject policy.
Security
DKIM Setup Guide: Key, Selector, DNS
DKIM setup step by step: generate the key, pick a selector, publish the TXT record in DNS and verify it with dig. Example records and common DKIM mistakes.
DNS
SPF Too Many DNS Lookups (10-Lookup Limit) Fix
SPF too many DNS lookups error: what the 10-lookup limit means and how to fix it. Counting include, mx, a, SPF flattening, macros and checking with dig.
DNS
SPF Record Explained: Syntax and -all
SPF record explained: v=spf1 syntax, include, a, mx, ip4 mechanisms and the ~all vs -all difference. Example records, dig commands and common SPF mistakes.
Security
How to Get Off an Email Blacklist
How to check and get off an email blacklist: Spamhaus, Barracuda, SpamCop. dig commands for DNSBL, listing causes and the step-by-step delisting process.
Security
Emails Going to Spam: Causes and Fix
Why your emails land in spam and how to fix it: SPF, DKIM, DMARC, IP reputation, content and blacklists. Step-by-step domain diagnosis and DNS record checks.
Monitoring
Diagnosing Intermittent Downtime
Site goes down intermittently and you can't catch it? How to diagnose flaky outages: continuous monitoring, multi-region checks, a health-check script, and API.