July 15, 2026
How to read a DMARC RUA report (and what it reveals)
A DMARC RUA report is a compressed XML file. This guide dissects the structure, decodes each useful tag, and turns that XML into an action plan.
Read →Blog — page 5
July 15, 2026
SPF macros and the exists mechanism: going beyond the 10-lookup limit
SPF macros with the exists mechanism authorize unlimited IPs in one DNS lookup, the only real way past the limit of 10. How it works, what it costs.
Read →July 14, 2026
DMARC reports: RUA vs RUF, what's the difference?
DMARC RUA reports aggregate statistics, RUF detail a single failed message. Contents, who still sends them, privacy risks, and which one truly matters.
Read →July 13, 2026
How to verify the DKIM signature of an email
Verifying a DKIM signature: reading the DKIM-Signature header and Authentication-Results, checking alignment, and why a valid signature can fail.
Read →July 12, 2026
DKIM 1024 or 2048 bits: which key size to choose
2048 bits is today’s DKIM standard and 1024 is on borrowed time. The DNS 255-character trap, and migrating an old key without breaking signatures.
Read →July 11, 2026
DKIM key rotation: why, when and how (without breaking anything)
Rotating DKIM keys limits the impact of a leak. The dual-selector method, the right frequency, and the trap of retiring the old selector too early.
Read →July 10, 2026
How to generate a DKIM key (and publish the right one)
Generating a DKIM key means a private/public pair: one kept secret, the other published in DNS. The steps, the key-size choice, and the alignment trap.
Read →July 09, 2026
What is a DKIM selector (and why there are several)
The DKIM selector points a receiver to the right public key. What it is, where it appears in a signature, and why one domain often carries several.
Read →July 08, 2026
SPF for Microsoft 365 and Google Workspace: the setup that works
SPF for Microsoft 365 and Google Workspace, separately or together, without busting the 10-lookup limit. The right includes, traps, third parties.
Read →July 07, 2026
SPF PermError: what it means and how to fix it
An SPF PermError makes the record impossible to evaluate, so it is ignored. Causes: 10 lookups, syntax, void lookups, duplicates, and the fixes.
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