Understanding DMARC
DMARC connects the visible sender domain to SPF or DKIM. A published DNS record alone does not prove that a message is correctly authenticated.
Read articleKnowledge base
Email security starts with understanding how things connect
Short technical introductions lead directly to the relevant check. No invented studies, rankings or hidden results.
Operating SPF safely
SPF permits specific IP addresses to send for a technical sender domain. Receiving servers and the visible sender address serve different purposes.
Read articleMaking sense of MX and DNS
MX records describe a domain’s inbound mail path. They are neither an approved sender list nor proof of a working SMTP service.
Read articleConfiguring MTA-STS correctly
MTA-STS publishes transport requirements for incoming email through DNS and HTTPS. Both parts must match the actual MX servers.
Read articleUsing TLS-RPT effectively
TLS-RPT requests aggregate reports about SMTP transport encryption. It provides observations from other mail providers and does not enforce encryption itself.
Read articleFrom a one-off check to monitoring
A correct policy today does not prevent later DNS, certificate, routing or sending-source changes. Continuous checks provide a history.
Understand monitoringResult code directory
58 documented codesTechnical findings clearly explained
Each permanent page explains a finding and its next step. Codes remain available independently of any domain result.
Check your domain
Start without signing in. History and alerting require a verified domain and an available account.