July 06, 2026
How to check an SPF record (and what to actually look at)
Checking an SPF record is not confirming it exists: it means reading its syntax, lookup count, qualifier and alignment. The complete step-by-step guide.
Read →Blog — page 6
July 05, 2026
SPF -all or ~all: what's the difference, and which to choose
SPF -all or ~all: what the terminal mechanism tells receivers, how ?all and +all differ, the interaction with DMARC, and which one to publish.
Read →July 04, 2026
What is SPF flattening (and when to actually use it)
SPF flattening swaps includes for the IPs they resolve to, to get back under 10 lookups. How it works, the maintenance debt, and the alternatives.
Read →July 03, 2026
SPF 'too many DNS lookups': understanding and fixing the 10-lookup limit
The PermError “too many DNS lookups” breaks an SPF record past 10 resolutions. Why the limit exists, what counts toward it, how to get back under.
Read →July 02, 2026
Is migrating to DMARCbis necessary? The no-stress checklist
DMARCbis replaces RFC 7489 but stays backward-compatible. What should change in the DMARC record, what must not, in which order, and how to verify.
Read →July 01, 2026
The end of the pct tag: DMARCbis's t= testing mode
DMARCbis drops the pct tag for t=, a binary testing mode. Why pct disappeared, how t=y behaves, and how to roll DMARC out gradually without it.
Read →June 30, 2026
DMARCbis's DNS Tree Walk: the end of the Public Suffix List
DMARCbis replaces the Public Suffix List with the DNS Tree Walk to find the organizational domain. How it works, why it is more robust, what changes.
Read →June 29, 2026
The DMARC np tag: locking down subdomains that don't exist
DMARCbis adds the np tag for non-existent subdomains — a spoofing gap that sp never covered. What it does, how it differs from sp, and how to set it.
Read →June 28, 2026
RFC 9989, 9990, 9991: what actually changes in DMARC
DMARCbis is made of three RFCs that replace 7489. What each one contains, the exact list of tags added and removed, and what it means for the record.
Read →June 27, 2026
DMARCbis (DMARC V2): what actually changes, in plain English
DMARCbis, published in May 2026, replaces RFC 7489. What the DMARC V2 revision changes (np, t, DNS Tree Walk), what stays, whether action is needed.
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