Articles & Guides

Enterno.io study: Russia's RKN registry holds 131,361 domains, 70% are international (not .ru), and 19% of the world's top sites are blocked. Data + method.

Enterno.io scanned 50 of Russia's top sites: only 2% use CSP, 25% use HSTS, and 57% score an F on security headers — while SSL/TLS hygiene is excellent.

Mail server monitoring: checking MX, SMTP ports 25/465/587, TLS via openssl, blacklist status and alerts. Set up continuous mail monitoring in enterno.io.

Warm up a sending domain and IP for email: a day-by-day volume schedule, gradual ramp, starting with your most engaged subscribers, and reputation monitoring.

How to make transactional email land: a dedicated subdomain, SPF/DKIM/DMARC, stream separation, and MX/SMTP monitoring — practical, battle-tested rules.

Why emails bounce: SMTP 5xx and 4xx codes explained, the real causes — bad address, reputation block, SPF/DKIM/DMARC failure — and how to fix each one.

How to handle email bounces: the hard vs soft difference, SMTP 4xx and 5xx codes, suppression-list rules and automation to protect your sender reputation.

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.

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.

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.