The DDMARC Blogdeliverability
Field notes tagged deliverability
7 field notes tagged deliverability. Back to everything.
01DKIM Key Rotation: Moving to 2048-bit Keys Without Breaking MailMove DKIM from 1024-bit to 2048-bit keys without failed signatures: new selectors, split TXT strings, overlap windows, and the Google and Microsoft quirks.deliverabilitybest-practicessetupOct 14, 20268 min read02SPF Too Many DNS Lookups: Fixing the 10-Lookup LimitOne include can cost seven of SPF's ten DNS lookups. What counts toward the limit, what a permerror does to DMARC, and how to get back under it safely.deliverabilitydmarcbest-practicesOct 14, 20267 min read03The 0.3% Spam Rate: How to Monitor and Stay Under Google's ThresholdGoogle requires bulk senders to keep their user-reported spam rate under 0.3% — and really under 0.1%. Where the number comes from, how to watch it in Postmaster Tools, and what to do when it climbs.deliverabilitygooglepostmasterAug 24, 20264 min read04DMARC Passes but Email Still Lands in SpamPassing SPF, DKIM and DMARC is the entry ticket to the inbox, not a guarantee. Why aligned mail still gets filtered, and how to find the real cause.deliverabilitydmarctroubleshootingJul 20, 20265 min read05Microsoft 365 Sender Requirements EnforcedMicrosoft now requires SPF, DKIM and an aligned DMARC record for bulk mail to Outlook.com. Who is affected and how it compares to Google and Yahoo's rules.deliverabilitycompliancemicrosoftJun 30, 20264 min read06DMARC Rollout Playbook: p=none to p=rejectMoving from p=none to p=reject is where most DMARC projects stall. A staged, evidence-driven path to enforcement that will not block legitimate mail.dmarcdeliverabilitybest-practicesMay 26, 20266 min readrev Oct 202607Google & Yahoo Sender Requirements 2026The 2026 Yahoo & Google bulk-sender rules — SPF, DKIM, DMARC alignment, one-click unsubscribe, and the 0.3% spam-rate limit — in one checklist to confirm you comply.deliverabilitycompliancegoogle-yahooMay 12, 20264 min readrev Jul 2026
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