Guides
Short, clear guides on email and domain security, in plain language with concrete steps.
Stop spoofed email with DMARC
How to stop anyone from sending email in your name. A clear walkthrough of how SPF, DKIM and DMARC fit together and how to reach p=reject without losing legitimate mail.
SPF and DKIM for Microsoft 365
What SPF and DKIM are, the difference between them and how to set up both for Microsoft 365. Plus the 10-lookup limit that silently breaks SPF.
DNSSEC: worth the effort or not?
What DNSSEC protects against, when it is worth turning on and how to do it at your DNS provider and registrar. And why it is not mandatory.
What does the KOLLEN grade mean?
How the KOLLEN grade from A to F is calculated, what drags it down most and why it measures what is visible from the outside, separate from PIANOLA's Risk index.
Fetch the grade via API (JSON)
The full check's result is available as JSON without a key. One call, the same grade as the result page, and with raw=1 the records verbatim. 30 calls per hour per IP.